Since you have AHP/CM15A try putting the TM751 on a unit code that is higher than the modules.
Having a TM751 on the same HouseCode won't interfere with AHP sending PLC commands, unless you are also sending RF commands at the same exact moment.
At the same time, however, the TM751 won't do anything to HELP PLC transmissions from the CM15A, either.
I'm not sure why Dan suggested changing the UNIT code on the TM751 - the TM751 is hard-coded to Unit 1, and can't be changed.
It sounds to me like there is noise in between your CM15A and your modules that is interfering with the transmissions.
1) If you unplug the TM751, do the modules still work with Inisght remote? That would be another indicator of noise.
2) If you turn the units on with the remote, can you turn them OFF from AHP? That would indicate that AHP is not sending the right commands for them. They may need to be defined as "Old Lamps - non Soft Start" modules. This applies even for the WS-13A, for which AHP seemed to be sending Extended Dim commands if defined as a "Lamp" instead of an "Old Lamp".