This changed with Orchestator 20.3. You can no longer trigger jobs from Orchestrator for Robot of type Attended which includes Studio. You will either need to use UiPath Assistant to start a process locally on the host, or switch your Robot type to Unattended or NonProduction (which is not intended to license Studio and will present a warning notice when starting Studio)
This was announced in the following post which was also pinned to the the top of the forums From March 16th until March 30th.
Important . Starting with this version, you will not be able anymore to start a process from Orchestrator on a Robot of type Studio. In order to start processes from Orchestrator, you should use an Unattended Robot. Each Community account has 1 Unattended Robot included.
if you search the forums for similar topics, you’ll probably find a decent amount reiterating these details.
BrianaB
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