@HectorSMG The text adapter is separate from the Windows adapter, so the NewScreenShowing event should be unaffected by how the application is launched as it is simply connecting to whatever HLLAPI session you've configured. In this case, I would suspect that when you start the emulator, you are doing so differently than when a user starts it. Perhaps this user is using a different session file, or has some additional arguments they pass to the emulator when they start it. That is where I would start my investigation.
I understand that the way the emulator starts has nothing to do with text adapter but the fact is that just changing the way of starting emulator, the behaviour of text adapter is different, maybe it is an indirect issue. In both cases the session is controlled and it is always the same one, A.
This robot works fine in another machine, so It doesn't seem an issue related to the development because in both machines the users and the configuration of AS400 are the same; scenario testing is the same in both machines. Maybe something related to the installation? some service? Some difference in any configuration file?
@HectorSMG Do you have the ability to use Process Explorer? If so, I would verify that the session is starting the same as on the other machines. Also copy the session file from one to another to see if that might be the cause. I suspect some difference in one or both of these. With Process Explorer, you can view the command line properties of a running process. Extract that for the working session and for the one that isn't working. Hopefully one of those things are different. If not, then this might require you to open a support case for someone to assist you on your machine.