are you using the latest version, which is v22.214.171.124908 ?
we fixed a bunch of FBX animation import problems in that release. So if you're not using that one, upgrading might solve the issue.
If you are indeed using the latest version, does it do this only with this animation or do you have other models/anims that exhibit this issue?
Ideally, could you send us an fbx showing the problem through the support email so that we might track the problem down on our side?