@uk_dave "You will only get changing background colours if the file is saved with a solid background colour and the user has their settings set to a different solid background colour."
Interesting info. Thanks for the clarification.
Hmm, nothing in our database indicating this is a known issue with ST8.
Only way to test and verify this would be to temporarily uninstall ST8, then install ST7 and open your ST7 files with ST7. Do they open solid or gradient?