Storage space is full while it is not, need to reset count of free space

I don't think it is the case. It says 10 of 10gb is full while actually only around 5GB max in drive.

And I cannot upload any files anymore.

Please refer to the issue https://support.box.com/hc/en-us/community/posts/20800651107475-recalculate-free-space

it was the same and was resolved only after admins executed some internal script.