Hi Van, 

Welcome to Box Community and I'm here to help!

We've corrected your storage count. To verify this, log in to box.com> Account Settings> Used Storage. 

Let us know in this forum once get this issue again. https://support.box.com/hc/en-us/articles/360043695334-Storage-Usage-Or-File-Count-In-My-Account-Is-Incorrect

Thanks for posting!

I am having this same issue. I only have 4 small files in Box yet it will not let me upload through Box Capture as it says I am out of space.