looking at, i think i have a theory as to why. the bones on models have "b-" in the front as prefix. as a result, when retargeting the bones, they don't work because the names aren't the same as the default unreal model bones because they don't have the prefix. i tried seeing if i could remove the prefix on the engine, but didn't seem to work because i think it extends to the animations too. hoping that may explain the issue and how to possibly fix it.