I have an odd problem. I am running a Flashforge Dreamer with buildtak sheet on the bed, and things, mostly ABS, are sticking too well onto the bed, making them really really hard to get off. I am running extruder temps around 220-230c (Depending on the ABS color), and bed temps of 110c and the items stick like they are superglued. Even getting a corner up means I have to pry every mm of the item up. The bases of the object also look a little white as well, so maybe this is a helpful indication, and it's not coming from the buildtak - that's blue, brand new and nothing white has ever been printed on it.

Heating the bed back up does help a little, as with no heating I have been unable to even start prying the items off, but heating seems to weaken the bond ever so slightly and allow me to get a spatula under the item to start.

PLA sticks great and once you get a corner up it just pops off, and that's with a bed temp of 50c, or 60c at night when the temps hover below freezing in the shed where the printer is located.