I've 'discovered' (idk if anyone's reported it or anything) an incompatibility with 'Customizable Player Models' in which having a megaring renders the player unable to view their body without crashing the game, which also prevents the opening of the inventory.
I assume it's something to do with how the ring renders on the arm, and how CPM allows you to edit your model causing a crash because the game doesn't know where to put the ring.
I am able to play just fine when CPM is disabled.

Although I haven't tested, I'd assume the same happens with the rest of the mega accessories and the dynamax band

Hi there!

We've recently released a new version (9.1.4) with a lot of fixes! Please re-test your issue, and if it still occurs, please make a new ticket with relevant /battlelog, latest, and debug logs.

Thank you!