The one thing I just realized I may have missed in the PCA9555 hookup is the INT line going to ESP8266 GPIO12, but I don’t see how that might cause this kind of intermittent issue. It’ll take me some time to put together a schematic (but the basic idea is ESP8266 with a PCA9555, with BPE/BVE controlling optoisolated relays to turn on the booster and discharge the capacitor over the output section, and the other output GPIOs, COM included, going to a pair of L293D ICs…I realize this isn’t specific enough). There is some slight possibility it is a wire connection issue that only occurs when a station is enabled/disabled, but that seems rather unlikely. Something may be drawing too much current from the PCA9555 during a station state change, but that doesn’t seem right either, and not sure that would cause this kind of problem. The fact that the bug is so intermittent makes it tricky to troubleshoot….