Sorry if this isn't very good, this is my first bug report

Anyways, the Problem is Simple,

I create a super flat world in creative mode, and it works as expected until leaving the world, where Minecraft gets frozen on the saving world screen. No Crash report and the X in the corner does not work. Task Manager is the only way to quit.

I have also gone and put a super flat world on my server. This is much worse as the server software will not allow me to input commands from both the server-side, and client-side.

I am not sure whether this is a bug for just me or if others have had this problem. Thanks.

Of course, as soon as I try to get a video of it, It suddenly works again. I'm going to submit this anyways because it was a problem, even though it may be working now. And it does happen to still be a problem with the server. I will try to attach a video of the server software problem

Post-Read-through edit: The files were too big.