Well... I created a gnome warlock for testing. I have over 10 ranks in craft: general, over 10 in UMD. I took both Bioware and PRC crafting feats (Craft wondrous item, craft magic arms and armor, craft golem and Bioware brew mixture and craft wand). And I still can't take Maester PrC. In PnP the requirement is caster lvl 5th - here in PRC it's 3rd lvl arcane spellcasting - so I picked an invocation which is an equivalent of third level spell (Brimstone Blast), I have invocations of higher levels too...
What's wrong? It just doesn't seem to work.
EDIT:
Uhm, well... I'm sorry for this post. Anyway it seems that maester entry requirement does not acknowledge Craft: General. When I took some ranks in Craft:Armor and Craft: Weapon I was able to enter the class.
Anyway it looks like a little bug?
And one question - why do Eldritch Knight and Maester have full casting progressions? Is it impossible to code losing a caster level at first lvl of the class?