Resizing grouped text boxes causes preview window error
I was trying to resize three grouped text boxes, and the preview window began behaving oddly. It first caused all objects to disappear from the preview, leaving behind only the slide master (with the beige gradient). With a second attempt, the preview displayed the huge red X as seen in the attached screenshot. (The grey blocks in the image are to obscure confidential information.) Of the three text boxes, two used built-in animations and one used a custom motion path.
Undoing all the way back to the initial grouping of the objects does not restore the preview. Neither does switching between slides or scenes (although I note the preview window resizes in response to the presence/absence of the right scrollbar). Slide/scene/project previews work, but the preview window is still an X upon closing the preview. Timeline previews display the slide atop the X, and the X is left when the preview has ended. The recent preview issue involving Adobe Flash was completely resolved with the release of the ActiveX version 18.104.22.1680, so I'm inclined to believe this is unrelated.
I've saved to a new filename, but I'm hesitant to restart the program or reboot without more information for fear of losing considerable changes made in this one scene. Is this a known issue?