Since the most recent update to the CIQ Store Android app to version 2.6, I have been unable to enter negative values (e.g. -1 , -2, etc.) in any watch face settings using either the Samsung or Google pop up keyboards. That occurs, for example, when trying to enter a negative sensor temperature offset value in watch face settings with that option. There is a workaround, however, by accessing the settings via the Connect mobile app (Connect app > Garmin Devices > Select Device > Appearance > Watch Faces > Select Watch face > Settings). Hope this helps others who might also run into this issue. I am using a Samsung Galaxy S9 with Android version 10.
Update: I have also tried Microsoft's SwiftKey keyboard for Android with the same results. I also discovered that this apparent Connect IQ Store bug won't let me enter any special characters or symbols in the watch face settings.