As in the title, there is a fairly new mod which allows to place slabs in vertical orientation. But sadly Quark slabs aren't possible to work with this mod because, as autor of Slab mod said: "quark doesn't work because they do some really weird and quite frankly WRONG registration work and I'm not going to attempt to make it work manually." I know that Quark has vertical slabs but FirEmerald's implementation is a lot cleaner in my opinion. Stairs aren't working as intended too.

In addition this isn't a case in Botania or Mekanism.

Minecraft Version: 1.19.2
Forge: Newest
Quark: Newest
Dynamic Vertical Slabs and Stairs: Newest

Link to issue on FirEmerald's github: FirEmerald/AdditionalPlacements#6

I apologize for blaming this on create, it's not create's fault, I now believe it's because my mod is loading before create and the register events might not respect the event priority over the mod's load order. I need to find a way to ensure my block registration takes place after all other mod's normal block registration has taken place.
As an aside, I still believe AutoRegLib registers blocks/items/ect incorrectly.

Fixed by mod author