Holes have been showing up at random locations, at y=0 aligned with chunk borders

Possibly important details: this world was converted from the xbox 1 edition to mcpe, the process of hole generation has occurred basically at random and is continuing to get worse. (More holes), it is unknown whether or not blocks below y=0 are destroyed along with the bedrock.

Expected result: bedrock should be were it was left

Actual result: 16×16 holes spontaneously appearing in the bedrock

Postulation of Possible Procedure to reproduce the bug:

Create an Xbox one Edition world, with 1 layer of grass at y=64 and one layer of bedrock at y=0, upload the world to mcpe and repeatedly load and unload an area or leave and return to the wold several times until holes are found in the bedrock

and/or you could attempt to create a facsimile of the wold described above on a superflat and see if you can reproduce this error in a world that was not uploaded from the legacy console edition