Ok, so I managed a work around this morning. Follow the steps below -
Check first to see if you are running PMS version 1.19.1.2645 (Public) or version 1.19.2.2673 (Beta). If the latter, follow the steps below.
Unfortunately, the instructions given above to set the Secure connections to ‘Preferred’ and leaving the ‘Disable weak TLS versions’ box unticked does not work for version 1.19.2.2673.
First I had to change the ‘Server update Channel’ in PMS Settings/General to ‘Public’, roll back my PMS and perform a server update to 1.19.1.2645.
You will find previous versions of PMS in ‘C:\Users\ * YOURNAME *\AppData\Local\Plex Media Server\Updates’. You will need to allow to show hidden files and folders to access AppData.
You need to then uninstall PMS from your PC using Control Panel/Programs/Uninstall Program. DON’T WORRY, you will not lose your settings or media! Do not use any other program but your Windows built in ‘Uninstall Program’ to uninstall and DO NOT use a registry cleaner like CCleaner to clean the registry.
Once uninstalled and with a previous PMS update in ‘C:\Users\ * YOURNAME *\AppData\Local\Plex Media Server\Updates’, install Plex. Once installed restart your PC. This is not necessary, but just to be safe, I did.
Once booted up, open PMS and update PMS to 1.19.1.2645 (Public - Make sure you are not installing the Beta version or you’ll be back to square one).
Make sure to set the Secure connections to ‘Preferred’ and leaving the ‘Disable weak TLS versions’ box unticked.
Test your Samsung TV Plex Orca app and it SHOULD now work.
Hope this helps! It worked for me 