Xbox - skill button assignment changes at every transition and support gem level up

I play Hexblast Saboteur and this evening have had a very weird issue. To be clear, game worked fine around 3 pm BST but since I logged back in around 6.40 BST i've had this:

The game automatically switches the x button assigned to the hexblast skill (supported by minefield and 4 more gems) to be detonate instead evwry time that:
1) i transition anywhere: hideout to mine encampment, mine encampment to mine, hideout into a map, out of a map, et etc
2) every time a support gem levels up, which has been a lot as i just used the quality recipe on 4 support gems last thing when i played at 3ish.

The transition thing i can deal with, although it is annoying. Having to disable auto-levelling on the support gems to avoid dying when they level up mid-fight and i suddenly don't have my attack skill is really not on though!

I tried logging out of tbe game, quitting the game and logging back in. This did not resolve the issue.

I saw a similar post elsewhere, and it seemed to be related to the mine mastery 'Detonate mines while moving'. One work around seems to be to have your main weapon+shield in the weapon swap (and have the 2nd set active instead of the first one).

Here is the other thread: https://www.pathofexile.com/forum/view-thread/3508532