Could the Preferences items have been reactivated due to a crash for example?
I re-checked the boxes I mentioned above and restarted Ps.
I assume they fixed the bug that led to having to uncheck the boxes in the first place.
As far as I know the bug was not yet addressed in the 19.1.1 update.
You are correct that the PNG distortion issue is not resolved in today's release, Matt.
This problem should be fixed after the Photoshop 19.1.2 update. You can install this update via Creative Cloud desktop app.
Also, you can refer the list of the fixed issues after the Photoshop 19.1.2 update, here: Fixed issues in Adobe Photoshop CC