Tangrid get confused after wakeup from sleep

We are on beta 1.4.0. Using a tabbed layout on MBP. When Waking from sleep often (always?) a lot of the tabs are missing that where visible before going to sleep. Say from 10 tabs only 4 survive the sleep. The apps are still active, windows visible but not organized by Tangrid anymore until activated and Tangrid can grab them again.