J3.2.2
Have tried both K2 2.6.7 and 2.6.8

I got loads of categories, items and almost as many extra field groups/extra fields. Making my site quite complicated

This doesnt happen with all categories, only a few and its not obvious why. If I edit a category, the Associated "Extra Fields Group" is set to "None" for some categories that were previously setup and assign an EFG. Only realising what happened after I edited a category that had auto set the EFG to None, did I realise this causes massive issues in it seems to remove all extra field data from all items that were previously assigned to this category - thats now been saved with a None EFG. I've had to redo so many items. I've tried renaming extra field groups to have shorter descriptions and not include characters such as - , . " ' etc - this worked in one case, but not in others.

I'm more than happy to akeeba my solution and share it with K2 developers to investigate further.

Please assist me, we're 2 weeks into this project, and its due this week, I really cant afford to redev :(

Hi. So you edit a K2 category with an associated extra field group and it is losing it's setting? Or this happens randomly? If this is occurring randomly check for any third-party content or K2 plugins.

YES to: "So you edit a K2 category with an associated extra field group and it is losing it's setting?"

BUT

Its not happening to all categories, only a few, but when its happening to a category, its always happening to that category. IE: if category 1 is not pre-selecting the extra field group, it will always not pre-select for category 1. IE: It doesnt randomly not work for category 1 and then another time does work

We've also noticed, that while using this website over the LAN (the host dev machine and one other connecting to website via LAN), the one PC will show the extra field group but the other one does not. Its really strange.

I'm thinking, this is possibly happening because we have so many EF groups and so many categories, its simply getting confused, or its information overload, I dont know :(

Which browser are you using? Check the browser console for javascript errors in pages that extra fields are not preselected correctly. Also try to clean the browser cache just in case.