Not 100% sure I understand, but I’m wondering if you’ve set up one of your Ones as a separate system, and not as a surround speakers to your Beam. Try unplugging the One temporarily, then start up your controller. It should, I think, connect to your Beam (and maybe the other One? I’m not sure how it reacts when the surround connection is ‘broken’.
If it does connect, then you need to factory reset that currently unplugged one, the use the ‘add a device’ in the controller to re-add it to your system. Then, you should be able to add the pair of Ones again as surround speakers (although you may have to remove the remaining One as a surround, first…your system may be in an odd state), before re-adding both as surrounds.
Oops, forgot the ‘if you don’t believe me or you’ve misunderstood’ clause…
You may want to call Sonos Support to discuss it.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.