oMLX w/ Splash doesn't work with Ornith-122B-oQ3e-mtp

[MyCometG3]

I am trying the Ornith-1.5-122B-oQ3e-mtp model, which I manually quantized using oMLX 0.7.3.
It runs well with the oMLX native engine, but when I set the external engine option to Splash, it always fails to load with errors like
the following:

Model 'Ornith-1.5-122B-oQ3e-mtp' failed to load:  
Splash exited with code 1 while loading Ornith-1.5-122B-oQ3e-mtp:  
error: checkpoint has missing or unsupported shards:  
model-00001-of-PLACEHOLDER.safetensors,  
:  
model-00012-of-PLACEHOLDER.safetensors  
error: model download or verification failed (log: /Users/foobar/.omlx/logs/splash/omlx--Ornith-1.5-122B-oQ3e-mtp-25b0ac07.log).  
Reload models after fixing the files to retry.

I searched existing PRs, issues, and discussions, but I'm not sure whether this is a known issue.
Does anyone have any idea what's going on or how to fix it?