I corrected it by doing the following:
I opened the Inspector, going to Appearance, then checking the theme. I changed the theme back to "Classic". I went to layout background and remove the background color.
I still have erroneous characters that have also appeared since the FM15 update.
You should avoid using Classic as a theme now; it was only there to accommodate layouts designed prior to the introduction of themes. Try creating a new report layout, even if the problem seems to have been resolved for now.