Troubleshooting 404s and Redirections
Redirected to Homepage for non-admins
Estimates and Invoices with the status of "Temp" will redirect non-admins to the homepage. Fix this by updating the status to "Pending" if yet unpaid/accepted.
404 Page (plus Redirection plugin)
When viewing some estimates and invoices you're may be redirected to a 404 or the homepage if you're using the Redirection plugin. The cause of this is a setting called "Monitor changes to posts", set this to not monitor changed posts and the bad redirects should be fixed.
404 Page (plus WP Depender plugin)
The .htaccess file is likely being modified by WP Depender which adds a setting to "Prevent PHP execution" and won't accept a refresh of permalinks.