For some reason, as of today (December 12, 2017) I am unable to save any pages which have a % symbol in the body of the document.
You also are unable to save any inline comments which use a % symbol.
Regular comments work fine.
Its very easy to reproduce:
Both work fine for me. Try a different browser, otherwise, open a support ticket.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.