Hot on the heels of 4.2.16 beta build 7765, this build fixes a new issue when saving images at 8-bit color depth if they have transparency (as reported here and in a few other posts: https://forums.getpaint.net/topic/118074-autodetect-bit-depth-on-saving-png-files-fails-on-beta-4216776543041/)
To get this update, make sure you have "Also check for pre-release (beta) versions" enabled in Settings, and then click on the Check Now button. (Unfortunately alpha/beta releases are not currently available for the Microsoft Store version of the app).
You can also download it directly on the forum.
- Fixed an error when trying to save images that have transparency at 8-bit color depth