Max 2025.1 PNG sequence not saving alpha

[Dchimenti]

Hello, crew.

I'm rendering a simple animation and saving as a PNG sequence and no alpha is being saved. 

-I'm using Arnold

-Yes, "alpha channel" is checked in file's setup

-tried it with both arnold render view and regular render view

-both render views are showing the alpha. but it's not making it to the file

-I've used photoshop, AE and "view image file" in max.  All not seeing an alpha channel in the file.

BTW- if I render a single frame and save that manually, I get an alpha channel in the PNG. This is only happening when I render a PNG sequence.

I've attached one of the files to this post.

Thanks.

[Dchimenti]

While trying to STILL resolve this issue, I discovered that any animation created in Max 2024 and loaded into Max 2025 IS saving an alpha channel in my PNG sequence.

I even loaded an animation made in Max 2024 into Max 2025,  deleted all elements, and imported/merged an animation made in Max 2025 and that animation is now rendering alpha in my PNG sequence.

So, something about creating animations in Max 2025 is blocking it's ability to save alpha with PNG sequence files.

[raineiroandres_coboscastro_qs]

I have similar experience when I trying bake some maps, none of them came out with alpha despite the standard png setting.
This always bugging me and I decide to analyze what would be.
I think I'm close but I don't know what is the exact root of the problem.

I found two troubleshoots for this.
First. choose "Save File" and setup the png settings, next, select the preset "3dsmax.scanline.radiosity.draft", load the preset, then, go back and choose Arnold in Renderer option, and Render. Now you can see the PNG with alphas embedded.
Second. When you choose the file name, select (overwrite) some previous PNG which had transparency and Render.

Hopes this works, if I found a more logic way to improve the fix I'll let you know.

[climax3dcgi]

I Found that the new color space default is the issue (OCIO), i changed it back to gamma in Rendering>color management and it is saving alphas in png, i guess that is why if you open a scene from previous versions it renders normally as they were created using gamma workflow
Is it there any setting we should change in OCIO for rendering images with alpha channel?

[MartinBeh]

Looks like a limitation in OCIO in 3ds Max to me. Switching to Gamma Workflow bypasses the OCIO part.

I can reproduce the incorrect alpha channel with Arnold and Scanline rendering, as long as OCIO is active.

[MartinBeh · Accepted solution]

Someone from Autodesk told me this is a known bug and also showed me a workaround:

Select an existing PNG file with correct bit depth AND alpha before you enter the new filename/path. 

Or, as reported here: work in non-OCIO mode, i.e. use the legacy Gamma workflow.

[eric_elftman]

That works.  Odd bug.  Stranger it's a bug in two version.

[Dchimenti]

Yeah. So fun being tech help for Autodesk and not being heard. 🙂

[r_white1]

Thank you ... I would never have found that out by my own experimentation.   Kudos to you.

[alan_camerer]

Max folks: This is a MAJOR issue. Just wasted 3 hours render time - 1200 frames, thinking it was working fine but came in this morning to black screen pngs. 

PLEASE fix this. Not acceptable to have to click on an image from an older version to 'fix' it. 

[cjohnson324]

 

I had the same issue on previous scenes for Max 2025.3 and Arnold, both the fixes listed before fixed it where the Alpha would save out with .pngs :

"First. choose "Save File" and setup the png settings, next, select the preset "3dsmax.scanline.radiosity.draft", load the preset, then, go back and choose Arnold in Renderer option, and Render. Now you can see the PNG with alphas embedded.
Second. When you choose the file name, select (overwrite) some previous PNG which had transparency and Render."

New Issue: Skydome with Light Shape Visible keeping Alpha Channel from rendering. 
So I had a new issue where it wasn't rendering the Alpha Channel at all (wouldn't show up in the Preview Render or when saved out), and I had started from a previous scenes that I had no issues with for the last 3 projects. It wouldn't render the Alpha Channel at all, when you hit the Alpha Button in the Render Preview, no Alpha. I tried a scene that worked and imported all the geometry and cameras and lights into a scene that would work, and it still would kill the Alpha Channel. 

The issue I just realized was I had One Arnold Light set as a Skydome and I had previously tested an Environmental Map in the background and there is a setting on the Skydome of "Light Shape Visible" that was messing up the Alpha Channel. Once I turned off Light Shape Visible, it started rendering the Alpha Channel.

This is what I got when I googled it, I'm sure there is a reason for having this turned on if you are using an environmental background you are going to render, but that seems like a big issue otherwise:

In 3ds Max 2025 with Arnold, the "Light Shape Visible" option for a Skydome light is not directly available as a checkbox. Instead, the Skydome light's visibility in the render is controlled by the Environment settings and the "Visible to" parameter within the Skydome light's properties. If you're using an HDRI map for the environment, a Skydome light is automatically enabled, and its visibility is determined by the environment settings. 
Here's how to manage the Skydome light's visibility:

1. Using the Skydome Light directly:

Create a Skydome Light: Go to the Arnold tab, then Lights, and select Skydome Light. 

Adjust Shape Rendering: In the Skydome light's properties, navigate to the Shape rollout. You can enable or disable the "Light Shape Visible" option there. 

Visibility Settings: The "Visible to" parameter within the Skydome light's properties allows you to specify which ray types (camera, diffuse, specular, etc.) the light is visible to, effectively controlling its visibility in the render. 

Autodesk needs to fix some of these basic issues with Alpha Channels and put out more information about Arnold issues in general if that is going to be the new renderer to replace Mental Ray. I never had so many issues with Mental Ray as I have with Max 2025 and Arnold.