Snap - Cannot Save Edited Email Template "Could Not Create Directory"

I have Nextcloud snap 110.4 stable installed on Ubuntu 16.04 Server.
I enabled the Mail Template Editor
I can edit the HTML code on "Public Link Shares (HTML) by going to
Admin > Additional Settings > Mail Templates
But when I try to save the edited Template I get an Error
"Could Not Create Directory"
Also the only Theme I can select is “example”

The output of Nextcloud log in Admin > Logging:
Error PHP
mkdir(): Read-only file system at /snap/nextcloud/1182/htdocs/apps/templateeditor/lib/mailtemplate.php#98

This is a Snap install so is that what is causing the issue?
If yes, then how can I edit and save email templates?