Glass Beds and Even Heating

[Martin_au]

Post some photos of the bottom of your prints. It could also be plastic shrinkage. Most plastics shrink a bit as they cool, and can then pull themselves off the heatbed if not securely stuck.

There's a few brands/types of filament that are particularly problematic. It may be worth trying a few different brands to see if you can find one that doesn't warp much.