Associate BMC with proxies
Subnet has no association with Proxy, therefore Foreman picks up proxies with BMC features "randomly". When there is nothing found, it uses first proxy with BMC feature available. This is based on an assumption that all BMC proxies has direct access to all servers which is not the case.
The solution is to create new BMC association so Foreman uses the correct BMC proxy for operations associated with the BMC interface. To prevent confusion, I suggest also to remove the fallback mechanism - if no association is found than use the "first" proxy available. We should explicitly error out instead.