This was purely a hosting issue. Thank you to Steven for going over and above trying to solve this for me.  In the end, a provider change got me up and running again.

Everything seems to be in order, however, I am experiencing the same issue of being kicked to the login screen every time I attempt to make any changes to the site.  I will send an email with the URL and login details.

Thank you for the response. I will start working through your suggestions. Just to clarify, I have run the Server Compatibility Test recently and everything passed, and the clean install of the site was attempted after the issues started to appear.

I have recently encountered a problem in the admin menu. Any change I attempt to make to the site results in being logged out and taken back to the login screen. I have been using Showkase without issue for two years, my server is 100% compatible, and I have just completed a clean install of the software including a browser cache clear and I continue to encounter the same issue.