Weird rendering when loading schematic.
Just recently updated to the 1.12 version of this mod and this occurs now when I load in any schematic.

Mods loaded are: Schematica-1.12-1.7.8.162-universal || LunatriusCore-1.12-1.2.0.40-universal || OptiFine_1.12_HD_U_C4 ||
Here is the log file from forge: https://pastebin.com/yLU0iagZ
Removing optifine resolves the issue temporarily but this issue never occurred on previous versions. Not really an issue for me, just informing you so that maybe this issue could be resolved :)
https://github.com/Lunatrius/Schematica/issues/246#issuecomment-320862337
I'll check if there is anything that I can do to fix this issue.
Had same problem. Fixed by changing version of optifine to previous. Schematica-1.12.2-1.8.0.168-universal LunatriusCore-1.12.2-1.2.0.42-universal OptiFine_1.12.2_HD_U_D1 >> OptiFine_1.12.2_HD_U_C9
I think it is problem of optifine, not schematica.
If anyone is still looking for answers... Turn off shaders :)