after a longer absence, I updated from 4.6.1 => 4.7.0 => 4.7.1 => 4.8.0 => 4.8.1
so I can't say in which update the "bug" happens.
If you try to change the order-status you will get a blank page after the process and no email is sent, too. The status is changed correctly in the database but only after a manual page reload displayed correctly in the shop.
This is a minor issue but would be nice to get fixed.