Linux: Saving or exporting always says "0% disk space"

In Windows I’ve been editing with Shotcut just fine. I’ve booted back into Linux, and if I try to save a new project, or export a file, it doesn’t matter if I choose a Windows partition or a Linux partition, it always gives an error that “0% disk space on this drive, save anyway?”

If I click Yes, it goes through the export, but it saves under some temporary folder under /run/user/1000/doc, then some random letters. But actually browsing to that folder after it’s done, reveals an empty folder! Same result for trying to save the project XML.

Looks like I’m stuck with using it in Windows unless someone has heard of this bug?