Dear Aardvark,

Thanks for the big reply:

I think I'm spoiled with the undefeatable Tiertime Up Plus and Up Mini 3d printers.
The Up Mini prints 200 micron, super fast ABS and never ever had any problem at all with cracking, not sticking to platform (perforated board = the best way) and the Up Plus prints 150 micron and also superfast, fill density at minimum, solid as a rock. Flashforge simply doesn't do that.

I only want ABS for the option of acetone smoothing and PLA support structure is terrible to take off.
+ PLA had the same result at the same height with the crack.

Indeed it doesn't look like shrinkage or cooling down since it's only cracked at a certain height and everything else looks good.

I will add the cube and match the height and print that, thanks!
I do have PLA.

Do you have any suggestions for the speeds I'm using? What numbers should I use for 100 micron on ABS?

Flashforge has a max temp of 240, which is very low and I looked over it when researching a new 3D printer, Up Plus has 270, Wanhao Duplicator 300 degrees. So I'm very limited in ABS filament choices. Is there a way to up the temperature to 250-270? I cannot do it in the Flash slicer software.

Thanks in advance for the answers!