This might be happen due to below reasons.

1. Internally, SharePoint manages a hidden list named "TaxonomyHiddenList". URL of the list is - "[sitecollectionURL]/lists/taxonomyhiddenlist".
2. Generally, All authenticated users (everyone) has Read access to this list.
3. As a site collection administrator user, when I checked permissions of the list, I found none of user or group were having permissions to this list as you can see in below screenshot.

Resolution:

The solution was simple once identified. We should assign read access to all authenticated users (Everyone) operating within the site collection. Or We can delete unique permissions.

For Details you refer blog

This might be happen due to below reasons.

First login as site collection admin then do below process.

1. Internally, SharePoint manages a hidden list named "TaxonomyHiddenList". URL of the list is - "[sitecollectionURL]/lists/taxonomyhiddenlist".
2. Generally, All authenticated users (everyone) has Read access to this list.
3. As a site collection administrator user, when I checked permissions of the list, I found none of user or group were having permissions to this list as you can see in below screenshot.

Resolution:

The solution was simple once identified. We should assign read access to all authenticated users (Everyone) operating within the site collection. Or We can delete unique permissions.

For Details you refer blog