I seem to have the same issue reported here. Unfortunately there are no updates to that issue since August and I don't know if it was ever resolved.
In a nutshell, I installed Big Sur yesterday and now I have an issue where many of the apps I have installed won't show up in the search results, even after clearing the application cache and rebuilding the macOS metadata. Things I observed:
all the apps can be launched from Spotlight, so the issue seems to be only with Alfred ๐
if I launch one of the "missing" apps with Spotlight and then search for it in Alfred, the app still won't show up in Alfred's search results ๐คฌ
if I launch one of the "missing" apps directly from Finder, I am then able to launch it in Alfred as it will start showing up in the search results ๐คจ
I ran the troubleshooting on one of the apps that weren't showing up and these were the results:
This is also the first time that I installed a version of macOS on a separate partition rather than taking the whole drive - not sure if it might help troubleshooting the issue. Basically, I did the following:
create a new APFS partition on my SSD
launched the Big Sur installer, instructing it to install the OS on the new partition
once Big Sur was installed, I picked the option to import applications, files and settings from another installation of macOS, pointing to the partition where Catalina is installed