Automatic screen off ends the incoming calls

Good day Jolla Community.

By default my screen was set to turn-off after few seconds. Then, in order to access the OS, I needed to enter the code. I used the phone like this for a while.

However, I noticed that if a have an incoming call and the screen would be turned off or ‘closed’, the system ends the call without me picked it up. Is this a bug?

To circumvent this phenomena, i set the screen to turn itself off after 1 hour.

Please advise.
Thank you.
Eve