Topic: Master/cloud server setup: unable to flush cache

We've a master server with 7 slave/cloud servers and I've trouble clearing the cache; it will only flush files on the server that created the cache in the first place and I get this

Notice: Could not delete any cached files. Please manually flush the cache directory.

Is there any way to force BWPM to use a specific server or a workaround for our scaled setup?

Thank you