In creative mode ,I have found that there was cut that separates two pieces of land , it cuts over the dirt and the bedrock. The shape of cut is like a zig zag . The device I am using is Samsung Galaxy C5.
MCPE-33813
Big gap cut off the land in creative mode
Resolved
Duplicate
0
(Unassigned)
Unconfirmed
Phone - Android - Samsung Other (Specify in description)
Android 7.0
1.4.2.0
Retrieved
This has been reported before as MCPE-32175, please search before creating new issues.
Unfortunately, an update messed with how super flat worlds were generated and so if a world was opened during that version, the game wrote empty chunks to the memory when generating new terrain. This has since been fixed, however, the holes it created still remain, but new land should generate fine. If you want to patch them up, I recommend using the /fill command with grass.