when icolor alot of little tiles at once ....
minecraft verision 1.12.2
forge version 14.23.5.2854
littletiles v1.50-pre199-73

Should hopefully be fixed in the newest version, if not just post it here again.

I'm not sure, but maybe your graphics card is running out of VRAM. Maybe use the program GPUZ and send me a screenshot of it once the issue occurs again?