In some cases, the masked entry does not manage to accept the last digit when typing in, or directly setting the Value property. One example is this string: "169.254.1. 1". Note that there are two spaces right before the last digit. As a result of this, the mask displays "169.254._1_.___", which contains an incorrect value as it is missing the last byte.
If you use the Autofill from Contacts feature on iOS to set the MaskedEntry Value, any Value update inside the ValueChanging event is not respected in that case.