[BB_TX]

I found an article (and now can’t find it) that said in a circuit where a GFCI outlet is wired downstream of another GFCI outlet, when the downstream outlet performs a self check, the upstream outlet may see that as a fault and trip. During a self check the self testing GFCI creates an artificial fault to ensure the fault is recognized by the GFCI SENDOR. Still trying to find the article again. But could possibly be what you are experiencing.