tested with MB3 created movie.xml.
2014-11-18 21:23:23.6528 Debug - Auto Box Sets: Found box set 49066 with 2 members.
2014-11-18 21:23:23.6818 Info - App: HttpClientManager GET: http://api.themovied...anguage=en,null
2014-11-18 21:23:23.8048 Error - App: Error getting response from http://api.themovied...anguage=en,null
The remote server returned an error: (404) Not Found.
at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
2014-11-18 21:23:23.8048 Info - Auto Box Sets: Unable to verify collection ID of 49066 - not creating set.
the error logged by the boxset plugin highlighted that i had lots of movies marked as belonging to a boxset which TMDB did not agree (the boxset) existed.
Some of the phantom boxset could be explained by previously created boxsets on TMDB which had been removed by some jobs-worth deeming them not worthy and removing.
But others looked like MB3 may have incorrectly fetched previously, eg 'sleeping beauty' and 'chicken little' belong to same, no longer valid, box set.
in any case the issue being reported is..
MB3 does not refresh this value either automatically or manually with an advanced refresh when the current tmdb value is blank and the mb3 value is populated..
if the tmdbcollectionid value has changed on tmdb, it does get updated, but only on an manual advanced refresh.