After updating to Virtual Office Mobile (VOM) v 7.2, you notice that all messages from February 2018 are showing as unread.
Virtual Office Mobile v 7.2
If you chatted with another user between December 2017 and February 2018, but haven't chatted with them since February 2018, these messages may come back as unread. You will need to mark them read again. If you see a large number of old conversations come back as unread, please let us know.
This is a known issue with VOM v 7.2.
For more information, see the New Messaging Experience FAQ.