Yes, the slots are there just not visible in the Hierarchy.
I forgot to mention, the Slots doesn’t show up in wTabMenu’s Hierarchy either. So I would guess constructing them in wDebugMenu and adding it to wTabMenu wouldn’t work.
As you said, I think it’s a Designer limitation. Tried swapping out the NamedSlots for Buttons, the buttons do visually show up but doesn’t get added to the Hierarchy tab. Probably can’t add stuff to the Hierarchy through Pre Construct. Which I guess prevents the Named Slots from working.
As a workaround, I manually added 10 Named Slots. Probably won’t need more tabs than that. Kinda ugly but works.