Effects Loop of Stage not mixing external pedal into all rigs properly

I created a performance with four different amps. I added the Effect Loop Mono at the end of the stomp chain just before the Output on all four rigs. I hooked up my Big Sky pedal and played a setting titled "Swell". It is an effect where you only here the ambient swell, like a synth with no guitar strings sounding through. All but one rig in the performance barely have any of the pedal coming through. I have one rig in the performance that it actually sounds correct. The Effects Loop is turned on and the mix is at 100%, volume is at 0 and ducking is at 0. The Mix is Post on every rig in the performance. Why does only one of my rigs have the right sound coming through?