Can't edit build items in categories

[apocthelegend]

I click edit build, I click on a category, I click to add an item to it or remove one, nothing happens.

Video attached.

 

[bambini!]

The most frustrating part is that sometimes edit works properly but breaks after some time for no reason

 

[Gooball]

I was a dummy. You have to have the category in your build selected first.

 

[Guilty]

I have the same problem

 

[t555bg35]

I have the same problem

 

[i319i]

Same problem here

 

[andreasvalentin90]

Same problem; I am unable to make any changes to my build.

I open Edit, select category, and press items I want to add - nothing happens.

 

[ArsleikCC]

same problem