Most unusual...
Boot into Recovery (Command R) and from the dropdown menu: Utilities> Disk Utility> run the First Aid on your Macintosh HD (and the "Macintosh HD-Data" volume as well if Catalina) If errors are found and repaired, run again until no errors reported.
Recovery: https://support.apple.com/en-us/HT204904
To trouble shoot further you can:
Try a SafeBoot https://support.apple.com/en-us/HT201262
Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Login and test. Reboot and test will take a little longer as caches get rebuilt— some times this is all it takes to sort anomalies like yours.
This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.
further:
Test issue in another user (or guest user) account https://support.apple.com/en-us/HT204443
This will tell you if it a universal issue or isolated to your user/admin account.