The corners aren't raising off of the bed, they are actually raising "up" off of the top of a print. For example when I print the horseshoe shaped print from the first post, the bottom is perfectly flat, and the top looks like a bedsheet if two people were holding it at the four corners. The middle is approximately 12mm (11.94-12.06), and the outermost edges measure 12.55 causing the top which should be flat to make a "U" shape.

I have mitigated it, but not removed it entirely by changing my default max feedrates to 200,200,2,17 and reverting to default settings in slic3r 1.2.9. Other changes to note (which did not affect print quality): I have upgrade from stock makerfarm firmware to the Marlin release 1.02 firmware, and now I am using the 1.1 RC2 firmware.

Old prints on left, new prints on right.

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