Heard a similar story from a guy on a maint hangar podcast where they pulled panels for days on a Caravan chasing an intermittent. Turned out to be a cannon plug that was only finger tight behind the panel. Vibration would wiggle it just enough to drop a signal and then it would come back. Wild how something that small can eat up two weeks of your life. Bet you check cannon plugs first for the rest of your career now.