In UMP Control Panel->Portal Settings->Display settings, right under the Logo section, there was no logo present BUT two options were displayed, for "Change" or "Delete."
How can there be a Delete option present if there is nothing displayed?
Therefore, I clicked Delete and the missing company_logo.png immediately showed up. I then pressed the Save button under the Display Settings to save it.
Log out of UMP (liferay portal), then log in and the company logo was now displayed in UMP and remained persistent.