Tab and slot flat pattern error

Solidworks 2018 added tab and slot feature. We do a lot of sheet metal work, and this feature is a big time saver.

However, we have been having problems similar to this:

That post was answered; I'm starting a new thread because I think the underlying problem has not been fixed. IMO it needs attention from SW.

Here's a part (attached, see screen shots) with tab and slot. As you can see none of the features are failing. Flatten it with sheet metal tools>flatten and it's all good. However as soon as you create a derived config, (i.e. for flat pattern) , the tab and slot features fail.

I use two plug-ins (NESTINGWorks and CustomTools) to export cutting profiles/ dxf's, and the tabs & slots are missing on the exported files. I've tried locking/ breaking references and nothing helps. I really need to use these plug ins, as they save hours of time. I can't afford to export every sheet metal part "by hand".

I think this is a bug, maybe SW can fix it in the next SP. (I'm on 2018 3.0)

SolidworksSheet Metal