EKXJ87 previously posted:
"Is the breaker you swapped out a GFCI or regular?"
Key question!
GFCI circuit breakers have been available for some time. If you had a problem with one GFCI, and had it replaced with another GFCI, it may be doing what it is designed to do. GFCI breakers and receptacles operate on the principle that what goes out, must come back. When I actually went to school for this (10 years ago), GFCIs designed for protecting people would trip with a 15 milliamp differential.
With proper grounding and bonding, a neutral wire with chaffed insulation can do just that.