New
#230
UPDATE:
New known issue added for KB4464330 in first post.
After installing this update, some users cannot set Win32 program defaults for certain app and file type combinations using the Open with… command or Settings > Apps > Default apps.
In some cases, Microsoft Notepad or other Win32 programs cannot be set as the default.In some cases, attempting to set application defaults again will succeed.
Microsoft is working on a resolution and estimates a solution will be available in late November 2018.
Yes, 7-Zip is another that cannot be set as default in 1809 or in 1803 (which has the same issue).
I didn't actually want to set it as default, just to add it to the list of available choices in 'Open with' by not ticking the 'Always open with....' box . That too seemed to be disabled by this bug.
I managed to add 7zFM.exe myself in Regedit by editing:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.zip\OpenWithList
After that I found I could set it as default (and back again to Explorer).
I don't keep a track of UUP much, but I just spotted this:
Cumulative Update for Windows 10 Version 1809 (17763.107) amd64