yes, im using .gtlf to load models with animations.
you can see: Com.jme3.anim Skinning Help - #7 by IkeOTL
well, about “Inconsistent animation sampling”
you just need sample animations to Linear in Blender:
in Animation → dope sheet → select animation → all(a) and T → Linear (there were something else to set Linear, but as i good remember the needed one was T → Linear)
anyway i use .gtlf not .glb so not sure if it have some differences in animation load.