I have the ring plus plan and all three cameras should be recording, but only one is recording and the other two are not.
This is odd to hear of, @Gatar73! The Protect Plus Plan will cover all Ring devices at one location, whereas the Protect Basic Plan will cover individual devices. Please check out your plans section by logging in at Ring.com to confirm the desired Protect Plan is subscribed. Please also double check in the Ring app, that all Cameras are setup under the same location.
While you are logged in at Ring.com, feel free to also check your recording history there for all Cameras, to see if they are being saved and will playback for you. I hope this helps!