This happened to me a couple times the other day, but I get it back everytime by doing the following:
Server.app -> Profile Manager
- Under Default Configuration Profile
- Click the "Edit" button,
- Then in the sheet, click the "Save" button. You do *not* need to change the name of the default profile if you don't want to.
But clicking "save" to forces an update to the Profile Manager settings, which seems to make the Trust Profile available again.
Try connecting again to "My devices" and see if the Trust Profile has magically reappeared.