Error when hitting "Update All Sites"

Hello -

So I've setup Multisite Privacy on a fresh multisite (sub directory), I went ahead and created 4 sub sites to test out this plugin. I am attempting to block access to all sub sites to non registered users. Under 'Default Setting' I ticked 'Only allow a registered user to see a site for which they are registered to.' and under Allow Override I ticked 'No'. When I go to check 'Update All Sites' and hit save I get a white screen with the note: "Applying to Sites, please wait... (4 of 4 updated)".

Once I do this, I am unable to access ANY of the network admin settings (plugins, themes, users, sites, etc) if I select any of them it just redirects me back to the 'Settings' page and the 'Update All Sites' is unticked.

Also on the front end of the site when I am logged out, I am unable to view Site 1, Site 2, but I can still see Site 3, & Site 4.

Has anyone else run into this issue? Is there a fix?