Saved pages content gets cut at current position and content is missing

When editing and syving a document it appears that content is missing.
Most of the time the document gets cut at the position of editing and the rest of the document is just missing.
Sometimes the last change is missing.
I just updated the Wiki to 15.9 and updated all extensions. So I am not sure if it is the WYSIWYG editor or other components involved. But it seems editing a document with the normal Wiki Syntax editor still works.