Some Win32 apps missing from Start menu "All Programs" list and search

I have a screenshot here where Outlook 2013 is not appearing on the Windows 10 "All Programs" menu on Start.

This is one of many examples that I have.  I have many other programs that are missing.  Which specific programs are missing seems to be random, most of them are there but maybe 10-15% are not.

Programs that are missing also do not show up in search results on the Start menu.  If I try to pin them to Start from File Explorer, that doesn't work either.

All in all, this is pretty annoying.  For apps that don't appear on Start, the only way for me to launch them (aside from pinning them to the taskbar) is to find a shortcut in File Explorer and launch it from there.

I've tried resetting the Windows Search index, and I've made sure that the "Start Menu" folder is included in the index.  Not sure what else to do.

Any ideas?  Thanks.