Snap version of LO cannot save to home directory, only subdirectories

I don’t normally use Snap apps, but I occasionally test out the Snap version of LibreOffice. In the past I’d found that Snap LO couldn’t write to the home directory, and I didn’t care enough to try to fix it.

This time, I discovered something even stranger: I could write to subdirectories of the home directory, like Documents, just not the home directory itself! The error message I get is:

Error saving the document Untitled1.odt. Object not accessible. Object cannot be accessed due to insufficient user rights.

Now, most of the subdirectories are symlinked from a data partition mounted under \media. But Desktop isn’t, and it works fine as well.

I also tried opening files from all three locations. Again, only opening from the home directory itself failed:

The lock file could not be created for exclusive access by Libreoffice, due to missing permission to create a lock file on that file location or lack of free disk space.

So it seems to me that this isn’t a problem with snap interfaces, but the home directory specifically.

Any ideas on what could be going wrong?

Software info: (K)ubuntu 18.04, snap/snapd 2.35, and snap LO