Email messages don't open

When I double click to open a message in the Inbox, it launches a new window. I can tell it’s there if I click on the EM Client icon on the toolbar, but there is no preview and it cannot be accessed. I have a screenshot.

I am running Windows 10 on a PC. Please let me know if you need further info.

Thanks!
Erin

Is this similar to the situation faced by @Louisd in:

My situation is similar but only happens with opening messages. I can click to compose new messages and get a pop up window without any problem.
I should have also mentioned in my original message that this issue is intermittent (seems to happen once a day and only started about a week ago) and can be fixed by closing the app and reopening. I am running version 8.1.1054.

Just a thought, I have other apps with issues because of the discontinuation of Adobe flash. Could this be the source of the problem? Adobe Flash Player End of Life