Issue description: Support Blocks not disappearing after turning off preview

Steps to reproduce: Turn on preview in builder, Adjust offset, Toggle the preview off and then back on.

Versions:

• Minecraft: 1.12.2
• Forge: 14.23.5.2847
• CompatLayer (only if on Minecraft 1.10 or 1.11):
• McJtyLib: mcjtylib-1.12-3.5.4
• RFTools: rftools-1.12-7.73

Possibly incompatible mods and versions: OptiFine_1.12.2_HD_U_F5

Relevant logs, if any:

Exact same issue here. If I reported, it'd be a dupe

This is a known issue and will not be fixed on 1.12. It's easy to get rid of the support blocks by right clicking them