ChromeOS  11021.56.0, 70.0.3538.76  beta-channel  eve	 

What steps will reproduce the problem?

No specific steps to reproduce the issue. 
1. Device was in laptop mode with few apps open. 
2. Switched device to tablet mode. Dragged the top most app downward to view all open apps in overview mode.
3. Dismissed all the open apps using swipe up/down action

What is the expected result?
Launcher should be displayed

What happens instead?
Launcher is not displayed. Only shelf and wallpaper are seen
Unable to open launcher by clicking on the launcher key.

Issue reproduced only once. Issue disappeared after switching device to laptop mode and then to tablet mode again.

Feedback report: https://listnr.corp.google.com/report/85740660204