MVP3 + TFV4 Mini issues

Heya,

Been using the MVP3 with an iSub G at around 25-30w for months without issue, I've now moved onto a TFV4 mini but it's been a bit problematic:

Firstly it doesn't work when the tank is fully screwed in, it needs to be undone approximately a quarter turn but the mod is super sensitive about the resistance it reads from it (the coil is rated at 0.35ohm and the mod reads anywhere from 0.3 to 0.5 depending on some extremely fine tuning), not a huge issue but a bit worrisome.

More importantly the coils I'm using run best at around 55w but the tank keeps resetting to 4v / 8w. This happens approx every 4-5 puffs under normal use, or every 1-2 if the unit is being charged. I'd guess it's detecting overheating but it seems to happen regardless of how hot the tank is running. Any of you fine people know what's going on?

Cheers!