I guess I’ll try taking out the GFCI & wiring the leads together but I’m thinking it’s a dead end since tripping the GFCI disconnects all the other outlets in the chain. Maybe pulling the dead outlets apart to check for issues would be more fruitful although maybe a broken wire somewhere?
My $.02 think you have good Info above,,,,,believe it May be a disconnected, broken or grounded hot wire.The GFIC’s are typically daisy chained as discussed above. Had a similar issue in a past trailer & turned out to be a grounded hot lead, but no indicators in fuse panel. & impacted the GFIC’s similarly . Tracked each junction box,,, Had to check each junction box, pulled the fuse box cover & traced each circuit,,finally found cuplrit abandoned that run,,,pulled a replacement run & tied into daisy chain circuit back into behind fuse box. PIA,,,but was covered under warranty cuz we discovered it after a PDI @ dealer showed operational, but after dealer delivery & set up was non functionsl. Hope this helps,,,good luck👍🍀🌞