Latest from Sil about this getting fixed is:
No, that is indeed the community server issue that I also mentioned above. It is happening intermittently and we will be addressing that in the next available client version.
and
The next client version will be early in January. It would not have been wise to risk any new client versions this close to the holiday season. We are aware that the intermittent issue with the community server is effecting some raids and grouping, and that will be resolved as soon as possible in the that next client update.
So be aware over the holiday period about this - it's not great but just have to live with it...






