Saved Logins not available in 10.5

We're received a few complaints that after upgrading to 10.5 the saved passwords are not available.

Steps to reproduce:

1. Install Tor Browser
2. open about:config
3. Flip browser.privatebrowsing.autostart
4. Flip security.nocertdb
5. Optionally flip signon.debug, devtools.console.stdout.chrome, devtools.console.stdout.content for debug logging
6. Quit Tor Browser
7. Start Tor Browser (again) with verbose logging on stdout
8. Open about:logins (or Logins and Passwords under the Hamburger menu)
9. Click Create New Login on the lower-left
10. Input text into the fields
11. Click Save
12. See failure messages