I need to amend my post, Alberto.
I have a copy of my test app in a folder (that was one of the pieces I used in the webinar on July 5).
I don't know which version of NetTalk it is using... its clanet.dll date is 5/23/2019. If I send a request to an API server, have "enable proxy" specified, and have Fiddler running, the app hangs.
When I recompile the same app with NetTalk 11.19, it DOES work with a proxy (Fiddler, in my case).
It's not the DLL - I copied the May 23 DLL into the newly compiled folder and it still works with Fiddler.
This may be completely unrelated to the issues you're having. And I don't have anything more recent than 11.19 to test.
Cheers,
Jane