What sort of density are you seeding the cells at in the wells vs in the flasks?
Ratio of medium : cells?
That sort of behaviour (the sticking to the bottom) is often a sign of differentiation in these sorts of lines IIRC, which is what makes me think it is something to do with seeding density.
Thanks for your message.
Seeding density is the same as in the bottles and range from about 5 X 10^4 to 5 X 10^5 cells/ml, which is what we were told keeps the cells from developing e.g. IL3-independent growth...