Blender 3.6
BST 3.2.6
SourceIO 5.4.0
Decompiler 10.0

I downloaded an animated model from asset.party, which as I understand hosts files made for a mod to the Source engine https://asset.party/anomidae/cute_rat/version/16508
I imported the vmdl_c file using the Blender SourceIO importer, which worked fine. The model looks correct and it's rigged. But SourceIO does not support extracting animations.
So I used the ValveResourceFormat CLI decompiler to extract the dmx animations from the vmdl_c file.
Trying to import the resulting dance.dmx file with BST resulted in a string of "Animation refers to unrecognised bone ___" warnings. But all 24 of the bones listed DO exist in the armature. Opening the dmx file in a text editor shows a tree of bones that it's expecting. All of them appear to be in the right order and hierarchy, so I'm not sure what's going on.
The animation DOES get imported, but there's nothing in the timeline or dope sheet.
What did I do wrong?