Building Gadgets Version
1.0.6

Describe the bug
When using the Building Gadget in horizontal row mode, slabs place at the incorrect level compared to the currently placed slab. It always builds down a half-level from a slab that's level with block level and then you cannot build a row on top with the gadget. Switching to "Place On Top" mode will leave a gap between the currently placed slab and the build slab, exactly on half-level up

To Reproduce
Steps to reproduce the behavior:

1. Place a slab, make sure you can build a torch on it. That means it's at the correct level
2. Use the Building Gadget in Horizontal Row mode, any range. New slabs should be a half-level down with no way to bring them up the half-level
3. Attempt to place another row on top, you'll be unable to do so
4. Switch to Place On Top mode, new preview should be a half level above

Expected behavior
Slabs should be built level with the starting slab

Screenshots

Log Files
N/A

NOTE ON RUBIDIUM
Rubidium contains code that will crash many mods when used in conjunction with them. Unfortunately this includes Building Gadgets 2. There is absolutely nothing I can do on my side to prevent these crashes. If you're using Rubidium and your game crashes when rendering something, please try without rubidium before submitting a bug report.

Building gadgets can turn half slabs into double half slabs, so this is working as intended :). When you place above, you're setting the block height at +1, so its working as intended as well. Sorry! Its just the wonkiness of half slabs!