Level low spot in roof

When I bought this 1997 Georgie Boy Class C in 2014 it was literally like new inside and out.  Due to the wife passing away it had been stored inside and not used in 15 years.  I checked everything thoroughly before buying and the EPDM roof looked great and well sealed.  After the first rain I found a puddle which starts about the middle of the front cap and forms a long triangle where the deepest point is about 1/4" deep and 6" wide at the outside right corner.  Since everything was original I believe it was built slightly off and they shipped it out that way.  It did not leak and I see no evidence of it ever having leaked.  Due to its age I cleaned it up well. put several strips of Eternabond cut to minimize the low spot, then covered the entire roof with Liquid Roof, all on the same day.  At the deepest spot the Liquid Roof would have been about 1/8" thick.  Which I guess was too thick and now 3 years later about 6" of the Liquid Roof peeled up from that spot.  The Eternabond I put on is still well attached.  I cut off the peeled up piece and the remainder is very well glued down.  Since the water puddle is at the junction of the EPDM, the front cap, and the side cap, I want to level that spot out then recoat that area.

Since it has never leaked I really don't want to tear part of the roof off and take the chance of creating a leak.  This forum is great and I've read many posts about leveling floors but not about roofs.  Will flexible floor leveling work on the roof and what brand would you recommend for a roof?

It's not terribly unusual to have slight low spots in an RV with a flat roof (the better ones are slightly oval). The roof structure isn't all that sturdy and some sag is all-too-common.  It's considered a cosmetic rather than a structural problem and it isn't a problem unless the roof membrane develops a leak.

As you have learned, getting something to stick to EPDM, especially through wide temperature changes, can be challenging.  It takes careful cleaning & prep, and I would use an EPDM primer before attempting any overcoating. If you try a floor patch, make sure it is a flexible type cause that roof membrane squirms around a lot during travel and shrinks/expands with weather changes.

There are products made for leveling out "ponds" on flat roofs, e.g. Henry's Roof Pond Patch. I'd check some of those products for potential use. Again, flexibility and compatibility with EPDM are the key concerns.

https://us.henry.com/roofing/reflective-coatings/176-pond-patch

Dicor self leveling caulk will work too.

It is so nice to have this forum where we can get advice from people with so many years of experience.  Thanks!  Since Eternabond is reputed to be a permanent repair I'm going to leave it as is.