@dennism, thank you for reporting it. I confirmed this was a bug with version 20 of the Windows client. I pulled it off the site so the the link goes to version 19 again.
I thought at first that this was just an Avast issue because I get this issue even with version 19 if I've got Avast installed. The workaround for Avast users is to temporarily disable it during the TRIGGERcmd agent install.
EDIT: I created a new version (v21) that fixed the bug and includes v20's new feature for sending a command's result to the Runs list.
Sorry for the bug, and thanks again for reporting it.