_Sascha_

I don't know why, but since Alfred 5 the Spotlight search became somehow corrupted.
But I have no clue how it could be possible, because Spotlight isn't part of Alfred.
 
But with Alfred 5 upgrade, besides me the same issue appeared for two other users, too.
But we have fixed it, thanks to the "Rebuild macOS Metadata" Script:
 

 
But look out, if it really was able to delete the folder /System/Volumes/Data/.Spotlight-V100!
 
If not and you see a Operation not permitted error message, while he tried to delete the .Spotlight-V100 folder, you have to give the Terminal which Alfred executes when you push the button on the image above, full disk access via:
System->Security&Privacy->Privacy Tab 1. Pick "Full Disc Access" on the left panel 2. Pick your terminal on the right panel 3. Or add it from your Application folder (optional, point 5)  
 

 
Then Alfred should be able to delete the Spotlight Index File, if not or you want to do it manually, you can also do it by yourself, in terminal (with full disc access) via:
 
sudo mdutil -a -i off sudo rm -Rf /System/Volumes/Data/.Spotlight-V100 sudo mdutil -a -i on  
A bit patience and the Spotlight as like Alfred should find your applications or missing files again.
 
 
Maybe the developers could update the reindexdel.sh a bit
 
To check for a Operation not permitted from:
 
sudo rm -R /.Spotlight-V100 sudo rm -R /System/Volumes/Data/.Spotlight-V100  
And trigger a message to give Full Disc Access permissions to the Terminal.app.

+1 | Like this idea, nice enhancement for workflows

More detailed request, but already requested here.
 
+1 | Here, too.