Learn@UW has notified us of a reported bug in D2L involving TurnItIn (TII) Dropboxes that are copied/imported from another course. When Dropboxes are copied from a previous course where TII was already enabled, the new Dropbox will not be created on the TII side and submissions will not process.
Until we have a fix, all Dropboxes should be created NEW in courses, unless the source Dropbox does not have TII enabled. Learn@UW is working with D2L to get existing submissions processed.
If you have any questions or concerns about this issue, please contact UW-W D2L Support.