When adding 'submitter' to an input message to limit the users who can accept the next stage
When trying to proceed as a user without permissions there is no feed back as to why you cannot.
Trying to proceed as a user without permission on the overview page produces this error in Chrome Console
Trying to proceed on the 'Console Log' page produces this error in Chrome Console
Going thru to 'Paused for input' on the left hand side (only seems to appear when looking at console log) and clicking proceed without permissions does a full page post and does show some more information.
NB: You'll have the same problem (no feedback) even if you do not have a submitter if you are not logged in.