In Jobs perspective, an ad-ho job can't be created.
When New Job modal dialog opens and all relevant fields are filled out, clicking on Create button returns error with code 500.
From the error response, it can be seen that the reason for failure comes from container id being set to null in the request sent to kie-server. Ad-hoc jobs on the other hand, do not belong to a project and hence do not have a reference to any container in general, so either null is not allowed container id value on kie-server side for any kind of job (including an ad-hoc job) or an ad-hoc job can't be created anymore in the same context as before.