All of the different mass processors that might affect this makes it hard to know immediately what’s causing this, but it’s likely related to the UMassProcessor_CrowdVisualizationCustomData (If you’re in City Sample project) or UMassCrowdUpdateISMVertexAnimationProcessor. Specifically UMassProcessor_CrowdVisualizationCustomData has assumptions about the animations used in City Sample I believe and won’t work well for other animations. You might have to make your own similar processor (and make sure both aren’t running e.g. via tag filtering). I’d recommend using breakpoints in Visual Studio in those to understand how everything is connected.
Also this CSV I made of all the mass processors and fragments in City Sample which might help: Script to better understand MassEntity Processor and Fragment dependencies