Defective KFX modules?

So I’ve been having trouble configuring a SECOND working KFX fob module.

I originally purchased two complete wireless relay setups, both 1-relay boards with a KFX module. One configured normally and is working just fine. On the other, I have been having trouble with the KFX modules. The originally purchased one is still configurable in the base station software, but the pairing sequence for remotes no longer works (light remains solid on LEARN press and doesn’t turn off on second press, no flashing like on my working unit). I had another shipped and now this one doesn’t get picked up by the configuration software! It does pair correctly, though. Given I’m having no trouble working with the other unit, I imagine this must be hardware bad luck…

The base software, on the “defective” KFX, times out looking for a baud rate with the same settings that works for the other (via the ZigMo USB). I never get to the command config tool.

Is there anything I’m neglecting to check for troubleshooting or am I looking at a second RMA…?

Just guessing here: maybe completely power down the working KFX module. Perhaps it’s interfering with both of the other ones?