20.04 – Lockscreen does not allow to type in the keyword

I have the following problem – after updating to Ubuntu 20.04 and configuring gnome, the laptop goes into suspend mode when closing the lid. In 95% of the time, the lockscreen behaves as expected and let’s me type in my password. But sometimes (I haven’t figured out a trigger for that yet), the screen does not open the field to type in the password on mouse or key activity. The mouse works as expected, and the keyboard is responsive (for instance, the speaker mute/louder buttons work). The menu point PowerOff/Logout exists but instead of the ususal three choices Log Out/PowerOff/Suspend, it only has the Suspend option. The only way to get out of this situation is to restart the computer.
Any suggestion how to prevent this situation?