Hi @meisner
Look under User → Histories. Open the advanced search and set “status = all”. The size of each history is the amount each is using.
If any of the histories are only deleted, they need to be permanently deleted (purged) to free up quota space. To find all stray deleted datasets across histories, or entire deleted histories, go to User → Preferences → Storage Dashboard and use the functions.
After purging, go back to the top level page for the Storage Dashboard and click on the “refresh” button to recalculate the usage. You could also log out then back in again to refresh.