Steps to reproduce
Open any Affinity app
Choose [File › New]
Close the dialog or create a new document (does not matter which, as long as the dialog is gone)
Switch to a different application
Choose [File › New] again
Expected Result
The same dialog from before is shown.
Actual Result
The dialog pops up, but the thumbnails for the presets are invisible. They can be revealed by clicking in the area where they should be. This is what that looks like: link to screen capture.
Environment
macOS 11.1
Version 1.8.6 for all Affinity apps
Notes
I noticed this yesterday for the first time. I've been using 1.8.6 for a while. The latest macOS update was about a month ago.