Prusa Core One

Yes, Cura sliced code using MK3.9 presets works perfectly on the MK4, you do get a warning that the code is not sliced for input shaping but you just ignore.
So. then I took everything from the MK4 and put it on the Core one, AND IT WORKED PERFECTLY! The only common denominator is the build plate.
The build plate (PEI) was the one that I started with on the Core one. I might have mentioned before that the Core one heats the build plate to 150C to bring the chamber temperature up to 60C. I can only think that the temperature has somehow compromised the build plate, that's my next step is to try printing on build plate on the MK4.
While it may not be clear, the Core one using Cura code prints perfectly, once again you have to cancel the slicer warning.

CNC = Computer Numerical Control, the 1980's way of describing multi axis machines running on punched tape!

Tried the suspect build plate, yup, now only good for ABS!
 
So, if you want to use Chamber heating, do not use your precious PEI plate, 150C destroys it.
In as far as I am aware there are no caveats on the Prusa web site.

Haha - pink spaghetti!
 

One for the 3D print fans -