This wasn't on a BDS, it's console version.

When I'm making maps, the different level maps aren't lining up with each other.  For example, if i'm in the upper-right corner of a level 4 map, and I created that map from a copied level 3 map in that same section of the world, I run off the edge of the level 3 map to the right long before I hit the right edge of the level 4 map.  If the following helps, the seed is -1355577085. When I created the world, I changed the following from default:  peaceful mode, simulation distance to 10 blocks, friendly fire off, coordinates on.  I tried this on PS4(my issue is on Xbox1) with the exact same settings and the maps worked normally.