Apollo xp95 sounder base faulty

Hi all , I had 4 faulty addressable xp95 base sounders today , added them to a working Morley dxC 1 loop panel , it would not see the base sounders or the smoke detector on it. It also lost some devices on the loop as if it was isolating the circuit but without any isolated light . Anyone else have problems like this, no issues when i removed them and not had no wiring faults , also am I the only one who thinks the design of these make them awful hard to install to a loose u box through a ceiling tile.