Appium not working with numeric keyboard

I am trying to enter numbers in an edit field, though the field is focused Appium wasn't able to input the characters. I have tried it in multiple ways, all did not work. Example 1:

driver.FindElementByXPath("field_to_fill").SendKeys("value");

Example 2:

_driver.PressKeyCode(AndroidKeyCode.KeycodeButton_8);

Please help. What's the way forward?