Windows 7 Java 1.8.0_25 64bit
Normally blocks like sand or grass rotate randomlyand through their blockstate-file which worked in 1.12(MC Java Edition).
In the latest snapshot blocks tend to only rotate in the direction of north or south and it seems like these blocks create patterns. For example grass creates some sort of zigzag-pattern.
Besides that other variants of custom made block models create patterns like cakes or only rotate only north and south like the sword rack.
Also the blockstate-file gives the information that it should rotate radomly:
And my ovious guess is that only the first and third variant and not the second an fourth but i have no clue why this problem occurs in the latest snapshots.