No I haven't really nailed it down to a single thing.... possibly a combination of a few factors

1/
First up were the cloth wipes I use to clean off the dust etc when I prep-wash the primer. Prep-wash is used as a cleaner and removes any gums/glues/silicates etc that can contaminate paint, the cloth pack was left out of its cupboard for a few days so contamination may have occurred there.

2/
Heat may also of had an effect, after reading the directions I found it wasn't best to use in hot temps, specifically above 30dergee, it was 29 on the day and I did have the heater on as well so at a guess it would have been nearing 40degrees in the shed.
Also with this, I did shut down the heater in the cool of the evening, it was around 20degrees outside so perhaps the rapid temp drop had an effect....


3/
off chance this one but..... maybe I'd laid down the 2nd coat a tad heavy ??????
Usually I'll hang a light coat first and allow it time to tack off, just dry enough to touch really gently but not completely dry, pending on the day that tack off can be 15mins through to 2~3hours.
The 2nd coat I applied was hanging on well so I slowed the gun down a tad and laid it on a bit thicker.....




Before I resprayed the boat I did a test on an old car door I have here as a test bench, half was wiped down with the cloths and the other half done with new cloths, I also cooked it at 40degrees and laid down the same style of coats......
I still got the peel effect, mostly on the bad cloth side but had some on the good cloth side as well.....

So.....

combination I guess, contaminated cleaning cloths, way too hot for the paint.


I've eliminated the spray style as I used the same style on the respray that's come out perfectly on the boat.


The respray was also done on a much cooler day ~20degrees and without the heater being used at all.




On another note:
we had some steel work do the exact same thing, strangely enough it was sprayed by a co-worker on the same Monday I did the boat. The 310-UB beams had very similar patches of peel effect and again only in some areas, the boss put it down to the heat of the day and an extra thick coat of industrial paint & ...... someone that doesn't normally paint doing the job.

So I wont rule out Monday as one of the possible causes either