Somehow this ticket got messed up. Run the Integrity checker in the admin screen and see what happens to this ID. As a workaround, clone this ticket so you can start working on it.
Well the first thing to check is as Gabrielle said, the permission scheme. Look who has transition issue permission (or you can use the permission helper to find out if you have that permission). If you have that permission there is another possible restriction hidden in your workflow. Look at all transitions ("Begin Work" and "Suspend") and check what conditions are defined (there might be things like "only users in Role xxx can use this transition" or similar)
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG