Hello there @55f530e49b8543be97b030e4831225b6 !
No worries, you explained the issue clearly. This sounds like a corrupted skeleton asset, the engine is trying to access data tied to it (like your mentioned animation), then it crashes. So, we need to fix whichever corrupted/missing element tied to that skeleton.
The first step to try, would be to simply reimport the asset. Right-click on metahuman_base_skel and select “Reimport”. If the process fails, select “Reimport with New File”, and point it to the original MetaHuman skeleton.
Next, clear your project’s cache, via closing UE, deleting folders Saved, intermediate and DerivedDataCache from your main directory, then restart the engine, and allow it to rebuild.
If the issue persists, select your affected asset again, and apply “Fix Up Redirectors in Folder”, then “Resave Assets”.
In case the crash persists, then the last remaining option is to transfer the elements from the affected skeletion, to a new skeleton. Open both skeletons, then use copy & paste on each socket, to transfer to the corresponding bone. you will also need to re-assign any blueprints, mesh components, and targets.