Problems with negative temperatures

Since the latest OS 9.1 update, my Apple Watch Series 4 has had problems showing negative temperatures in the weather widgets. I am using Finnish language and Celcius as temperature unit.

In the watch mode the temperatures are always shown without the minus sign (actual temperature is -6 °C):

In the waether app the minus sign is shown for the current local temperature but not for the temperature range:

I already did a factory reset of the watch twice with effect. I also tried changing the language from Finnish to English, and the problem went away. Unfortunately it came back when I changes the language back to Finnish. So there could be some issue with the localization of the weather widgets.

Are there some other settings or actions that I could try?