I've printed with a lot of pc-max, and a common problem with it is that it has a tendency to warp up from the plate while printing. The material is very high temperature, and when I contacted Polymaker, they suggested to increase the build plate temp to 100C or even 110C. Additionally, I've had the suggestion to go into the g-code and turn off the cooling fan on the toolhead (or at least turning it down to 20%,) as that could cause issues on large prints.
The recent prints I did were on a Mini 1 Aerostruder; should be the latest firmware as I flashed it last week. In the past I've has the warping issue with Taz 6 Aero and Taz 6 Moarstruder as well.
Here's two of the prints where I had warping. I've been printing them with 80% infill and a skirt.
@matth Are you printing open air or enclosed? Using glue stick or printing straight on PEI? Is the toolhead an Aero V1 or V2?
Here is the feedback checklist we use so you have it for next time: http://wiki.alephobjects.com/wiki/General_Testing_Feedback
Updated PC-MAX Profiles for Mini 2 Aero V2 are posted here: T4547
I know you are using a Mini 1, tomorrow I will ask @karrad about pulling those same settings over into the Mini 1 profiles as well. Since its the same toolhead it should make much difference. There may need to be more testing to confirm for other toolheads.
Have a good one!