Not possibility to enter a - number in Settings with garmin connect for ANDROID

Hi.
In my application WF4TRAVEL i use the possibility to set several UTC . The variables are number

User enters in the settings from -12 to 14 the UTC

It's ok with an IPHONE on IOS but with an ANDROID the user can't enter the sign - so no possibility to set -2 for example

Why this difference between to OS.

It's OK with garmin express

Didier