@phaedrux
update - after making a few changes the hotend is now heating without the error.
The all metal throat is secured by two grub screws to the body/heatsink. Although properly secured, I think the throat was heating up, expanding slightly and making better contact with the heatsink, causing it to dump heat a bit quicker and triggering the error.
I've added some thermal compound to the throat/heatsink, re-tuned and can now heat from cold without any issues.
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