Reply from Drurabak after sending them photos and issue:

OK Thanks so much for getting back to use and giving us those details.

So, unfortunately, it appears that two things were not done quite per recommended guidelines.
First of all bare aluminum should have been scuffed 40 grit instead of 200 grit and the primer should have been applied straight away without a solvent wipe.

What happened is that the Xylene left a fine residue so that the primer couldn't actually bond properly.
The only way to rectify it with Durabak is to re-prep the surface as per instructions and re-apply - also, I am not sure if that Sherwin William DTM primer is the best option - how long after applying did you put the Durabak down?

I can offer you this coupon code for 20% off if you need to get more Durabak to finish the job.