Stack Overflow Error and other issues

Whenever my  friends and I go on an End expedition we get a stack overflow error. It permanently ruins the server and we have to revert to an older saved realm.  This never used to be a problem. We are now unable to get any new elytras without using the command prompt, which we try to avoid. Any way to fix this?

On an unrelated note, we used to be able to see much further, but now the chunk render distance has been severely limited. Any word on this? Will it change back to how it used to be? We can't even see across our city anymore and it makes flying and exploring nearly impossible as we just run into un-rendered terrain and can't see anything.