I could be wrong, but I believe that is a "feature" from A17 or 18. I remember people complaining of digging up gravel or asphalt around a POI and replacing it with something else. Then it would magically revert to gravel. It was described as "working as intended".That's one that bothers me; but, I was specifically referring to the issue where, if you dig up a block in the forest biome and replace it with snow, it still shows as forest; desert sand is ALWAYS sand, etc.