It is hard to tell looking at the screenshot but is the email and folder id the same? If you just have a Get then a Move does that work just to remove any extra possible issues from the workflow?
I guess it will be a case of checking the output of each node to see if any of them are doing anything silly or replacing a value with something else. It could be that it is just one item that is missing something, As a test maybe pop an if node before the Outlook node and only move forward if email_id and folder_id is not empty.
Hey @Jon - I’ve rechecked the thing and think it is due to the data format.
It appears that the parameter message ID is only working as a fixed parameter.
To do what you want to do you would need to use an expression which that field should support, I will set up an outlook account later today and give it a test.