Import/export of blender messing animation up

So I have this that i’m using as bones:
Sword And Shield Slash (4).fbx (224.1 KB)

it works perfectly:

however if i import it into blender 3.0.0:

and if i don’t change anything and just export it again:

this happens:

i assume its something to do with the scale export? but i have tried messing around with the setting but nothing happens has anyone experienced this who can help ?

tried with blender 3.2 still the same

This sounds like a bug in Blender’s FBX importer or exporter. It’s pretty common to see scaling changes with FBX, so tweaking those settings related to scale and units might help. But ultimately it’s a proprietary format that Blender had to reverse engineer to implement at all. We tend to advise using glTF files with three.js when you can.

It might also be worth trying the “Better” FBX importer/exporter, I haven’t used it but people seem to agree it’s better: