Unreal has a very old bug with it’s variables categories.
Variable category allows you to write category in 3 ways - “Global Category”, "Global_Category, “GlobalCategory” and Unreal will be “helpful” and will convert any of those options as “Global Category”
(sorry for the typo on the screenshots - I meant “camel case”, not “snake case” actually).
Which is all fine until you see how it looks in actor details. When Unreal draws details, it still treats those three as completely different, though still showing them as just “Global Category”.
So it creates a whole class of possible bugs:
- categories will appear duplicated
- in some cases sorting might break
- categories structure might get messed up
- dragging variable into “Global Category” will get “Global Category” instead of “Global_Category” which then will produce one of the bugs above in Details
- God knows what else
But there’s a workaround.
I don’t want to bore you too much with the details (also I’ve learned more about this than I’d like to admit), but the thing you need to know that Unreal the hood is trying to prioritize categories that written with space (e.g. “Global Category”) and stores them in a special variable CategorySorting on the blueprint.
But the thing is, sometimes it fails to do so. So the solution is to help Unreal converting categories to their spaced variant.
A workaround for this bug - is to always write variable categories as “Global Category” and never as “Global_Category” / “GlobalCategory” to avoid the consequences of this bug.
If you use any other naming convention, you will inevitably stumble upon bugs like this - [Minor] BP Variable Category Duplicates
Or your category sorting will break completely:
Instances of this bug I’ve found
Possible solutions for Unreal engine to fix this problem for good:
CategorySortingshould store categories as-is, not converting them to display format. Otherwise there will be bugs like [Minor] BP Variable Category Duplicates- Categories should be converted to display format, before used to group the properties and display in UI. That would prevent the example bug I’ve shown above.
The issue is present and tested by me in 5.5, 5.6. But given that one of the reports above comes from 2014 - so we can speculate that it’s at least Unreal Engine 4.3 or earlier. Got to have some respect for 11 years old bug.
Would be great if some developer can find this bug and fix it for good. If someone has a contact of developers from Unreal and can forward this issue to them, it would be also great.
I would try to report this bug to unreal report system, but it usually has almost 0 chance of success, unless you report some critical bug/regression in just released Unreal version. So I just keep it here in hope that this report will be at least googlable and might help someone to keep the sanity meeting this odd Unreal Editor behaviour.
Cheers.