Hello,
It appears removing ayatana-indicator-application and ayatana-indicator-common resolves this issue. Looks like dependencies changed recently, as apt suggested autoremoval of these packages when I performed updates today.
- Bug#905473: mate-panel: various application tray icons not ... Paul Bransford
- Bug#905473: Acknowledgement (mate-panel: various appli... draeath
- Bug#905473: mate-panel: various application tray icons... Mike Gabriel
- Bug#905473: resolution found draeath
