Treated Wooden Slabs(only horizontal slabs are shown below, but issue applies to all IE slabs) only give one slab when you break a double slab.

5 Slabs in my Inventory.

One bottom slab placed and one double Placed. 3 Slabs in my Inventory.

Another Double Placed, No Slabs in my Inventory

Broke the Single with an Iron Axe, Recieved one Slab.

Broke the Double with a Iron Axe, Recieved one Slab.

Broke the last Double with hands, Recieved one Slab. Started with 5 Slabs and ended up with 3.

IE Version is: 1.16.1-3.2.0-115
Forge is: 32.0.108

Tested this issue in a superflat world with only Forge, IE, and JEI loaded, Issue persisted. There is no crashlog to attach as no crashes happen.

Should Have noted that the Screen Shots are from the first test i performed, with all of my mods loaded. Noted at the bottom is a Second test i made, testing all of the slabs. The same issue cropped up where a double slab broken gives only one slab with all IE slab items. I saw no point to balloon this post with even more images when the issue was irrespective of other mods.