I have 4 GE AFCIs in a GE subpanel in my basement. Occasionally, when I turn on a bank of dimmable CFL lights via a CFL-rated dimmer switch, I get a trip in a particular AFCI breaker that's on the other phase. This doesn't happen every time, and it seems to happen more when the dimmer isn't set to full brightness. Resetting the breaker gets the power back on with no issues, but I'm tired of this.
I'm at a loss as to why a different circuit on a different phase is tripping, and even more confused why it happens only some of the time. These are not MWBCs, but obviously share the neutral in the panel feeder. Nothing else causes any other trips anywhere else in the house that aren't obvious, like 4 hair driers on a 15A circuit.
What's going on here? How can I find the cause of this?