How to sort and filter a constantly changing list of data?

I have a web page (although I don't think that's relevant, it could equally be a desktop or mobile app) that displays a list of events. More events arrive all the time, and are added to the top of the list as they arrive. We want to add sorting and filtering to this list, but I'm not sure what to do about incoming events when the list is sorted by anything other than latest first, or is filtered.

For example, if the user filters the list by (say) event type "Jim" and a new event of type "Fred" arrives, I presume I don't show it. The only thing is, they might leave the list filtered, and then not see most of the incoming events. This will probably confuse them.

Similarly, if they sort the list by (say) duration, shortest first, and a new event comes in that is of a longer duration than any shown, do I add it to the list? If so, does it need to be inserted in the correct place in the list?

Update In response to TripeHound's excellent questions, here is a bit more detail: The users will be watching the page during a campaign, and their main interest is seeing new events. They may filter to see what events particular users raised, they may sort to see what's been going on, who raised the most events, or the shortest, etc. So in short, it's very important for them to see new events.

Anyone able to advise. Thanks