Can't access second API when first was recently used within same APIM service

Question

I have two APIs in my APIM service. Each API endpoint has running Open AI service behind. When I'm using first endpoint (in my AI chat app) with one model deployed - everything is ok, but after that when I try to use another model in my chat app (I can switch between them in runtime) I'm receving an error from APIM service:

 "error": {
        "code": "DeploymentNotFound",
        "message": "The API deployment for this resource does not exist. If you created the deployment within the last 5 minutes, please wait a moment and try again."
    }

After some time when I start working with second endpoint and switch to first one - same error. Seems like APIM service is switching between these two APIs but can't handle both at the same time. How can I reconfigure APIM service to work with each API at the same time? APIM service has Basic tier