I doubt if it has anything to do with the propane tank, but there may be a automatic propane shut-off valve in the propane line near the tank. Clicking indicates an electrical relay opening/closing and the beep suggests that it is an abnormal condition. Your LPG (propane) detector will shut off the propane flow if it detects LPG fumes, so possibly that is happening? But that usually requires a manual reset to get the propane flowing again and you haven't mentioned that.
It is also likely that you have an electrical system controller under the bed - that's a common location in many Rvs. That may include an automatic transfer switch between shore power and generator. If you lose shore power voltage momentarily, the transfer switch may change positions. I never heard one beep, though.
Does your bed raise up on hinges so you can look at what is underneath?
+++ By the way, I have moved this thread to the Motorhome Problems section, where it is a better fit. It was originally in the General Discussion area.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL