Hi Juha_,
For help with with this issue, it's recommended you check your accessibility settings. Specifically Full Keyboard Access. The steps below found in the article here can help. Navigate your Mac using Full Keyboard Access
"Turn on Full Keyboard Access
- On your Mac, choose Apple menu > System Settings, then click Accessibility in the sidebar. (You may need to scroll down.)
- Go to Motor on the right, click Keyboard, then turn on Full Keyboard Access.
- Click the Info button to change the appearance of Full Keyboard Access (for example, the outline color). Click Commands to see a complete list of Full Keyboard Access commands, customize keyboard shortcuts for default commands, set shortcuts for advanced commands, or restore default shortcuts.
Tip: When Full Keyboard Access is enabled on your Mac, quickly show the Full Keyboard Access shortcuts by pressing Tab-H, then using the arrow keys to navigate the lists."
The guide page here can help you get started: macOS general accessibility features - Apple Support
You can also find helpful information here: Get started with accessibility features on Mac
Cheers.