Hi,
We seem to be having a similar issue, one of the ones that didn't auto attach did have the same email address against two accounts when we went to apply it manually, but others haven't and when we've clicked the apply to Request button in the mailbox it has found the correct request to assign it to so we've not been sure why it hasn't applied the update automatically. I think all the ones that have failed have been for calls that are on-hold, so I don't know if that makes a difference? We also seem to have had some emails automatically applied to closed calls (despite me checking the setting is off that allows updates to closed calls) but this doesn't always happen as when I try and test the emails end up in the inbox as they should.
Many thanks,
Jenny