I think I have conflict with some extension. I have uninstalled Additional Categories for K2, and now i can select 2 categories without bug. When i select more, same issue.
When you say the same issue you mean that even with the Additional Categories extension disabled you still have issues when multiple categories are selected through the menu?
Yes, with additional categories activated, I can just select 1 category without bugs,
witout additional categories I can now select 2 categories, if I select more, i have the same issue.
Maybe you need to ask for support on this from the developer of Additional Categories extension.
Either way, you will have to provide access to check on the issue.
Try to upload your site even in a testing environment.
