There are four elements you must be aware of, all marked here with a red arrow. If you set them all exactly like in this screenshot, it should show you every single model available.
(Model filter = All mods
Check subfolders = checked
"MDL files" chosen by clicking on it
Filter = blank
If you are looking for something specific, you can type a keyword in the "filter" bar)
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mvm_sludge |
koth_nippletwister
Works in progress (inactive, or haven't reached a satisfying playable state yet): ctf_hurricane, cp_glacius, koth_sprout, pl_thorndike, tc_feldspar