I am trying to import animations into UE5 from Blender, and the first one worked flawless, zero issues HOWEVER! the second animation, tied to the same rig shows all types of issues.
I have clicked ctrl + a to apply all transforms and t does nothing…
I don’t know for sure, because I don’t do anything with UE, but maybe I can offer some advice.
First, invalid transforms are going to be on some particular frame, right? So one of your first things to do is figure out what frame these invalid transforms are so that you can figure out why they’re invalid. You can do that by repeated export/import attempts, each attempt limiting the frame count by half.
Now, one of the messages gives you an explicit hint: zero scale transforms. Is that bone ever scaled to zero in any axis? Sounds like it can’t handle that.
For other bones, I’d first suspect similar stuff: weird scaling. A frequent place where this happens is in stretch-to bones, or bones with inherit scale disabled (or using weird Blender-specific stuff). There isn’t an actual transform for these bones when they’re inheriting non-uniform scale from a parent. A good workaround is to unparent these bones, or parent them to an unscaled root, after which their transforms should be valid.
But-- none of these bones sound like deforming bones, and I don’t know why you’d want them in UE anyways. Probably, you only want the transforms of the deforming bones, because those are the only transforms you probably care about. So why export all these bones? Export only deforming. There are probably easier ways to do this, but you could always bake action to a deform-only armature from your originally animated (and constrained) armature.
OMG THEY ARE AT 0! oops and thank you! problem solved 