I have found that non-breaking spaces will cause Confluece editor to have difficulty saving if there are too many of them. I don't insert these on purpose but notice that if I add a double-space, for instance, it automatically inserts one non-breaking space. I just wonder if there is way to find and, ideally, replace all non-breaking spaces with regular spaces.
And, to be fair, I am using the old editor despite this issue because of the ongoing limitations of the new editor.
