Sending a message to an user doesn't work if you previously sent another message to a group

Steps to reproduce:

1. Send a message to your followers or to a group
2. Send another message to an user

The first message will successfully appear on their activity stream, but the second one won't appear on the user's stream.

If you refresh the page (Main.WebHome) between steps 1 and 2 the message to the user will be sent.