Into Finder, when clicking on a color tag, loading unfinishing and finally no folders displayed as expected I have a bad experience with color tag into Finder. Indeed, when I click on red color tag, I expect the displaying immediately of the directories that I have associated to this red color tag (2 directories actually).
Here below an example of the issue : the french word &quot;Chargement&quot; means &quot;Loading&quot;.

As you can see, I am waiting for this loading and once this message has disappeared, nothing else appears, none of the directories associated to the color tag red.
If someone could explain me the origin of this issue and how to solve it, this would be fine to tell it.
I had this exact issue recently and these steps solved it for me.
First try to rebuild the spotlight database:

Open System Preferences and select Spotlight
Select Privacy
Drag your HDD icon from the desktop to this pane
Wait a second and then remove it.

This should rebuild the spotlight database on that drive.
If that fails you can do it manually using the command line in Terminal.
This command will do a system wide Spotlight reindex:
sudo mdutil -E /
This is a more extensive rebuild as it removes a possibly corrupt index database:

mdutil -i off /
sudo rm -rf /.Spotlight-V100
sudo rm -rf /.Spotlight-V200
mdutil -i on /
mdutil -E /

There are many websites and forums that explain how to do this.
https://www.macrumors.com/how-to/rebuild-spotlight-search-index-on-mac/