As of the last release, the ribbon in PBI Desktop (e.g. "File", "View", "Home | Publish", etc.) becomes unresponsive. The behavior does not occur on a consistent basis and only appears to have started since the last release.
The only workaround is to close the file and open it again. Please advise.
I'm also using the latest release (Version: 2.56.5023.1021 64-bit (March 2018)). However I didn't encounter your issue.
So in your scenario, I would suggest you to try to reinstall the Power BI Desktop. If the issue persists, you can submit a support ticket.
I had this issue for the first time today, I got around it by clicking the arrow in the top right of the GUI beneath the Close icon (^).
I clicked this twice, it hides the frozen ribbon then reopens it and upon reopening it was fully functional with all buttons displaying tooltip and the functionality returned.