The validation framework validates an input element and applies "k-invalid" class when its value is not valid to the hidden input. For such widgets like the ComboBox, DropDownList or NumericTextBox the applied k-invalid class is not applying to html-tags visible to user.
Hello,
The '.k-invalid' class has already been moved to the visible widget wrapper with the 2019 R1 SP1 release:
Regards,
Dimitar
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