spawn chunks removing placed blocks

Put the summary of the bug you're having here

What I expected to happen was...:
my blocks stay where I put them

What actually happened was...:
removes placed blocks.

Steps to Reproduce:
Interacting with end portals removes blocks that were player placed in the spawn chunks by the primary chunks borders. This has been an issues for well over a year now and nothing has been resolved. The fact that a company of this size is unable to fix something so simple is mind boggling. Dont dare reply saying I need a debug because I am not giving one. The debug wont help. I build base in the sky as spawn and whenever I come back from the end I have to replace three stacks of blocks that disappear from this buggy shit.