Hi James,
I am not sure if this answers your questions but I had similar problems.
I found this thread here:
…which explained how to turn PSM off, with AT+CPSMS=0 (not with an exclamation mark as shown in the preview).
Apparently it solved the problem of the FX30S entering either ULPM or PSM when the antenna was connected.
AT+CPSMS?
+CPSMS:1,“00011000”,“00001010”
AT+CPSMS=0
OK
AT+CPSMS?
+CPSMS:0,“00011000”,“00001010”
OK
I have only been using ULPM from Octave and pmtool from the command line so I have no idea how PSM have been enabled.