I am running the latest versions of Structurize and DoubleSlabs for my Minecraft version. No other open issue is the same as mine at the time of posting.

Minecraft Version: 1.16.5
Structurize Version: 1.16.5 (structurize-1.16.5-1.0.418-ALPHA.jar_
Related Mods and their Versions: 1.16.5 (DoubleSlabs-1.16-3.7.3.jar)

Expected behavior
Use build tool to place blueprints in creative mode by selecting the blueprint and then the green check mark.

Actual behavior
When selecting blueprints from the dropdown menu (using the build tool) that use DoubleSlabs entity slabs the game hangs and then crashes. Blueprints using vanilla blocks or a combo of vanilla and modded blocks (not DoubleSlabs) work as intended.

Steps to Reproduce
Scan a build (with the scan tool) that utilizes DoubleSlab blocks (two unlike slabs put together). Attempt to place this new blueprint with the build tool. The game will freeze and then crash.

Logs

crashlog.txt