Hmm... Have you had this trailer very long? Has it always had this problem or ??
Since the battery has power and fuses seem OK, I'd check the battery ground next. There have been a few posts indicating that can be a problem.
Sherm & Terry w/rescues Steve (std Poodle) & Eydie (min Schnauzer)
2015 Jay Flight 27RLS (Camped: 102 nights 2015, 90 nights 2016)
2006 Ford F350 6.0 PSD, Lariat, 4WD, CC, LB, SRW, auto., Camper pkg.