I didn’t personally implement the solution in that link from earlier, as I ended up avoiding the crash another way. That said, seems like it should work in theory, as the root issue for me was the same – my Pawn object disappearing.
I never figured out the nuts-and-bolts code reason why my pawn was getting deleted, but I did narrow it down to an issue with my character asset. I am using a pack obtained online, and it had something to do with the import settings on the skeletal mesh (or skeleton, or rig, I’m not sure, unfortunately these aren’t my area of expertise). Something was getting borked during the import process that set the bones’ scales weirdly large (or, the mesh weirdly small?).
For whatever reason, this had not affected anything else so far, such as setting up the animation BP, playing montages, etc. So the issue remained hidden until I began working on the motion warping.
Therefore my theory is it was something to do with the bad data in the skeleton/rig/mesh resulting in some weird/bad math results during the Motion Warping process that for whatever reason led to the pawn getting yeeted from existence.
I experimented with reimporting my meshes under different settings until I found something that now works (i.e. no crash, motion warping works with the model). These are the settings that worked for me:
However, I can’t say whether these settings would necessarily work for anyone else, as it may have to do with the way the models were originally created in Blender. I cracked open one of the .fbx files in Blender, but the scaling and unit proportions all seemed reasonable in there. However, I am not a modeler/animator by trade, so there could be something I was missing.
Anyway, hope this further information is helpful to someone. I am going to relink the post about how to edit the C++ to avoid the crash here so that I can mark this reply as a tentative answer with all the info in one spot.