Linux desktop client won't allow me to set sync folder on partition

I have Version 3.8.1 running on Manjaro Linux.
I’ve used it before for several months without problem.
After a recent sync issue, I uninstalled the client and reinstalled.
Now it won’t let me add the local folder as the sync folder. The one I have always used.
The folder is in a separate partition to my $HOME folder. It’s a partition that is mounted at /files, and symlinked from ~/files. I already have my local data in ~/files/nextcloud.

But when I try to select this folder in the client, the files symlink is greyed out in the chooser, and if I write in the location ~/files/nextcloud I get the error “you don’t have permission to write to this folder”.

But I do have permission to write to it. I can create and delete files within ~/files. It’s mounted with 777 permissions. I don’t understand why nextcloud is suddenly deciding that it can’t use this folder that it previously used without any issue. I’m sure this is not a permissions issue. Could it be a blanket problem with working with a folder that is on a different partition to /home/me ?

The desktop client does not support symbolic links as locations. See:

What was the sync issue?

You can also check your logs. See:

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