Media upload path issue

Hello!

I've got a multisite up & running with a couple of sites working OK, but I can't currently upload media to anything other than the main network site.

I believe the issue is to do with the upload path because its trying to upload to:

networkURL/sub-folder-site/wp-content/uploads/sites/5/2016/09/

But the path should be:

networkURL/wp-content/uploads/sites/5/2016/09/

One possible reason for this error is that the network site was migrated from a cloud server (tsohost) to my new VPS server... though I can't be sure this is the root cause!

Is this fixable?