It may worth mentioning that Electrum 4.3.2 has a change in its behavior, and may be exactly your "problem". The thing is that, from the others' point of view, this is a fix.
(fixes #7927).
With that update, electrum should regenerate an address that has been generated before in another request. if the previous request has been expired and the address has never received any fund.
Since OP has set the expiry date to never, electrum shouldn't generate the same address again. I don't think what's happening in OP's wallet is the correct behavior.