Mesh Deformer on editable object causes IPR to get stuck in infinite loop

[chatect]

Hey! Wondering if i'm missing a tag or something however, i've tried them all though so IDK if im doing something wrong or if its just a bug. But If I have an object that is editable and apply a mesh deformer to it and do whatever deformation I need using another editable object... Their seems to be a problem where if you open the IPR and make any change to any surface within the scene (so for instance, change the emission color of a shader from red to slightly redder), it sends the IPR into an infinite loop where it will not show any changes but try to update the scene and eventually c4d will crash unless you close the IPR and reopen it. 

This only happens if the object is editable, though. If you apply the mesh deformer to a (parametric? is that the word?) object, everything works fine. Scenes also render fine by the way, in both instances (editable or parametric),

like, if I animate the mesh deformer and render it out, nothing crashes. Its just when this is applied to an editable object and you make any changes to shaders while the IPR window is open.  But i'm wondering whats going on, if this is a bug or otherwise. Thanks for the help!!

EDIT: I should add I also discovered that adding whatever you're deforming to a layer including the mesh deformer, and disabling the expression, keeps the IPR from freaking out. If their wasnt a solution this can sort of be a temp fix

[peter_horvath]

Sounds like a bug, but I was not able to reproduce it based on your description. Do you have a simple example scene which you can share?

[chatect]

Yes! I made a scene and recreated the error. I checked it and the error still happened. 
https://drive.google.com/file/d/1qJXSrzWL73zqZ2mxImUksBAaIt8R6Q7r/view?usp=share_link

Thats the scene file. So if you open the IPR window, and with the IPR open, do something simple to either of the materials like change the base weight to anything less than one, the IPR (or at least mine) will refresh eternally until c4d crashes or you close the IPR window and re-open it. And then the changes you made will be reflected in the new IPR window. Then, if you delete the mesh deformer from one called 'this will cause infinite loop'... then make a change to either material, their shouldn't be any infinite loop. Everything works fine. Hope that makes sense 

[peter_horvath · Accepted solution]

If I change the material, my IPR does not go to an infinite loop, but it updates twice, so something's definitely fishy. From what I see this could be a bug or misbehavior in Cinema 4D itself actually. The dirty state of the object changes every time there's a change in the scene (like changing the object selection, etc.). I'll report it to Maxon, thanks.

[chatect]

Oh wow! thats wild. Thank you so much for looking into this! I really really appreciate your time. For now ill just disable the expressions when im using these to keep mine from crashing. I really appreciate you!!!