Ender 3 Max nightlies

Having a strange issue whereby none of the nightlies are working on my e3 max.
My slicer has a start gcode of g29 and it performs a 25 point mesh.
It takes an extremely long time for my extruder to hit and maintain temp (after PID tuning) and during the mesh, it wont maintain the temp.
By the time it actually goes to print the extuder has cooled to less than 100 degrees.
this is happening on all of the nightlies that ive tried so far.
Any help would be massively appreciated.

Yeah - the timeout for hotend protection would kick in.

You’re better off doing a G28, then G29 once, save the grid to the EEPROM via M500, and then skip doing a G29 before you start your print.