I received a used set of 1x MiniTT1 and 2 x FlexTT5s for cheap, played around with them a bit to find they were not triggering reliably so I downloaded the utility software and found a whole bunch of custom settings. I took this as a good sign so I updated the firmware and did a factory reset on all of them.
End result of which is:
Only one FlexTT5 will trigger when I'm using the MiniTT1, and it is always the same one. (Using the working FlexTT5 I still get the occasional missed trigger. I did check the PW blog and used their startup sequence ie. Flash, FlexTT5, MiniTT1, then camera.)
So far it seems like one of the FlexTT5s is faulty, except when I hit the test button on either FlexTT5, the other will trigger.
Any more troubleshooting steps to try before I entertain getting these looked at?