Hi Phiber,
Looks good, and looking forward to the taste test.
A couple of comments on the recipe: even 40 drops of annatto in a 2 gallon make sounds like way too much to me - I use 10 drops for a 4 gallon make. That said, your result doesn't look over-colored as I would have expected ... maybe different formulations of annatto with different strength of coloring action??
But here's the other thing to be aware of: annatto can interfere with the coagulation. As a result, you want to leave some time between adding the annatto and adding the rennet - at least 10 minutes. I'm wondering if you put the rennet in right after the annatto, and that is what caused the problems you had with a good set - that, or the quantity of annatto, or both.
Of course, one variable that is always in play is the question of the rennet. I know there have been a couple of discussions recently, so we may already have asked you for details on the type of rennet you are using, and/or whether you have tried liquid rennet instead of the tablets - ?