Problem solved by Olympus Technical Support (whom I've found very responsive and helpful so far).
For anyone who cares, here is their fix:
"The issue that you are describing is not due to a bug, but mainly due to a step that is missing, and not very clear in the manual.
"To enable this function, and allow this to work correctly as stated in the manual, please follow these steps:
"Press the MENU button, go into "Custom Menu" then select "Gear icon B" (button/dial/lever), then scroll down to the bottom option in this menu, the Lever 2 + buttons icon, press the right arrow to go into, then up or down arrow to change this to the ON position, then press the OK button to confirm the ON setting. Finally, press the MENU button again to exit, then try doing the procedure you describe one more time."
This gives EVF and Live View access to Flash Modes (bottom bar) and Flash Exposure Compensation (top bar) in Lever Position 2 by pressing the AF/Metering button.