locked 2.50.6 upgrade problems

Colin, G8NBO

I've been using WSJT-X 2.3.0 with JTAlert 2.16 for some time with no problems.
Today I updated JTalert to 2.50.6 and installed. Net 5 from the hamapps page. 
When I run JTalert the main window opens, I can open the decode widow.
There is no connection to WSJT, the Callsign window does not open and the About screen does not open. 
Also I don't get any sound when I try the sound test. 
Any thoughts on what has gone wrong? 
Colin, G8NBO

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