Dualboot stopped working after upgrade to Fedora 33

I have used Fedora on my Macbook Pro for a couple of years without hassle. I have used the Option key to select between Mac OS X and Fedora when starting up the computer.

Today decided to install Fedora 33, and now I can’t boot up Fedora any more. When I hold the Option button I see a screen with two choices (as images), Fedora and Mac OS X. But regardless which one of them I choose it is always Mac OS X that boots up.

I would very much appreciate help in this matter.

Best regards,