I get the issue now and again. I guess it's some sort of fleeting bug. I learned years ago that Max can be kind of tender and that an ENU reset is often the solution. However, when you do that, unless you take some care, you wipe out all of your customizations and plugins. With some prudence and technique, you can restore all of that but that's for a different discussion and help with restoring the ENU can be found here on the forum. I posted my workflow and you can find that as it details how I do it.
But, what I've incorporated into my weekly routine is that I back up my ENU automatically 3 times a week with a backup program that does it automatically. I keep two weeks worth. There are any number of backup programs that will do that so just choose one. Then, if you have a glitch, like this one, just go back to the last known good spot in time and restore that ENU and you are up and running again. Generally, unless you've installed a new plugin in the past day or so, you'll be going in just a couple of minutes like nothing ever happened.
I even have a shortcut link on my Desktop to my ENU folder and my backups are stored in that same place. So, if I have a problem I go to that folder, delete the 'ENU' folder there, find the backup I want and change it's name to "ENU" and restart Max. Problem solved in about 15-seconds.
Rob Holmes

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3ds Max (2023-2025), V-Ray 6.2, Ryzen 9 3950-X Processor, DDR 4 128MB, Gigabyte Aorus X570 Master motherboard, Sabrent Rocket NVMe 4.0 M.2 drives, NVidia RTX 4090, Space Pilot Pro, Windows 11 Pro x64, Tri-Monitor, Cintiq 13HD, Windows 11 x64
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