We have the same problem for all customers that uses load balanced servers. Sometimes the notification arrives to the other servers, sometimes not.
The sites is in EPiServer CMS 5 R2. We think that the reason is du to high traffic. The multicast packets are lost somewhere. The sites we have problems with has huge amount of visitors.
We've seen this aswell. We are running CM5 SP3. Its intermettent aswell - it usually works. Then one in 10 fails. For no obvious reason.
Is there anyway we can activate some sort of logging so we can track it down. Or atleast see how often it occurs?
Perhaps this article can provide some help:
http://world.episerver.com/en/Articles/Items/Cache-Update-and-Load-Balancing-for-EPiServer-CMS-5/
Don't know if it helps but maybe it's worth to have a look?
Thanks!, I'll give it a try.
Here is the tool mentioned in the article since the link was broken:
http://world.episerver.com/Downloads/EPiServer_CMS/Utils/EPiServerRemoteEventsListener.zip