That LM Studio log is the key clue: OpenClaw only ever calls:
POST ${baseUrl}/chat/completions
So if LM Studio is seeing POST /chat/completions (missing /v1), then the baseUrl OpenClaw is actually using does not include /v1 (or it’s reading a different config than the one you edited).
1) First, verify what OpenClaw thinks your baseUrl is
Run and paste the vllm/lmstudio provider section it prints:
openclaw models status
(That output usually includes the provider baseUrl it will call.)