@T3P3Tony - The heater does heat quite slowly, but that is due to the fact that the maximum achievable temperature is fairly low, something like 90C at full power. For obvious safety reasons. This is a PLA/PETG printer so really no reason to go higher.
It takes approximately 8 minutes to reach 50C from ambient, with an initial overshoot of around 3C, but it never appears to go out of the configured temperature window. I haven't put a timer on the appearance of the error to check the P parameter time. It's printing a large job at the moment but as soon as we can I'll check on that.
The issue is that there is no error if we are not actively printing. The error occurs at the start of a print job, even if the bed has been preheated to 50C and is set to 50C in the gcode.
The printer then pauses on error and bed halts. The temp error can be cleared with M562 but as soon as the print is resumed it halts within a short period of time (I need to time this). Clearing the fault some number of times (I need to verify the exact number) then seems to allow the printer to continue printing EVEN THOUGH... the error message pops back up but then it's no longer pausing the print.