This appears to be an Owl problem introduced with v0.7.7.2. By now v0.7.7.4 is out. You may want to give it a try, and restart Thunderbird after updating the add-on. Please report back your results.

Thanks for your responde.

Aluco versión is 0.7.7.4, updated today...and still having the same trouble as you can see next.

Inbox blank...click on other folder and click back inbox and all messages appear.

This is the advice I have received from the OWL people.

This was a known problem that appeared in the last few days. There is already an update available that fixes it for most people. Can you please install Owl version 0.7.7.4, restart Thunderbird (a restart is necessary for Owl), and see whether the problem persists? If the problem continues, please try to create a new Thunderbird profile, install Owl, and try to set up the account there. If it still doesn't work, please write to owl.support@beonex.com with a copy of your error console (Thunderbird menu | Tools | Developer | Error Console, and copy the entire contents as text), please.

Owl v0.7.7.5 has fixed it for me.

I restarted Thunderbird with the extension disable....then enable it for the second time, and i have been monitoring the app on my second screen, and seems the problem has been fixed......

Thanks for all of your commnets....