[BUG] progress being reverted by worldedit operations

[Solesey]

Describe the bug
When using some worldedit operations, recent changes in random chunks touching the region being worldedited will be reverted to an earlier state. This happens exclusively inside chunk borders. Ships recently spawned in with /blueprint load have had random chunks removed by other /blueprint load commands or worldedit. This also affects hand placed blocks. It is not client side, and I believe it is not a connection problem.

To Reproduce
Although the behavior is random, and possibly only due to my connection, you can attempt to reproduce it by spawning in a very large ship, then performing worldedit operations that touch chunks the ship is in, but do not harm the ship itself.

Expected behavior
Worldedit should only affect the region selected and no further.

Screenshots
in the screenshot with bare Heavy Lasers, they had node signs and glass placed on them prior to a nearby operation, resulting in them being reverted.

System (please complete the following information):

• OS: Windows
• RAM: 16GB
• Minecraft Version: Minecraft Java Edition 1.16.5

Additional context
as of yet, this has only been found on my beta plot

[gregolegomonkey]

Located two chunks where using worldedit/fawe causes issues: Spaceplots -108960, 39151. The chunks are marked.

I was attempting to //copy, //flip south, //paste part of one the thruster nacelles (on the north side of the ship) over my ship's X axis. The paste operation did not perform as expected- I used //undo twice and //redo once in an attempt to fix the damage, which was also unsuccessful. These operations seemed to revert the chunk to a previous state from before I moved the ship backwards (by shift flying).

Only the vertical chunks outlined by the slime blocks were noticed to be affected- the circled area in the 2nd picture is in a different vertical chunk and did not appear to be changed.