When TreatModifiersAsKeys = false, holding down shift and pressing a numpad key the key will be stuck as being held down

[DavidFidge]

Numpads can provide a functionality where if the user holds down shift and presses a numpad key then it will perform the alternative function on that key. E.g. Numpad4 turns into the left arrow key, Numpad1 turns into the end key etc.

When holding down shift pressing and holding one of these keys, then releasing shift, then releasing the key, the key stays detected as being down.

[DavidFidge]

This appears to be a bug in MonoGame itself. The key is still in a pressed state from MonoGame's KeyboardState.GetPressedKeys().

The workaround is to press the alternative key in and out, or hold down shift, press the numpad key and release the numpad key before releasing shift.