Image (e.g. imported scan) disappears when the glyphs outline are touched. Allthough View > Background is active, and image is locked. Only when a previous rotation of the image is set in the app, otherwise not.
What version of Glyphs do you have?
Several students had the problem using the last 30-days trial version of the full app.
Try the latest beta please. Go to Glyphs > Preferences > Updates, activate both checkboxes and press the Update button. Should also work in the trial period.
Yes, is fixed here.