ABAP RAP Value help as List box

[Kostiantyn_K]

Hello, colleagues

I faced up with very weird bug or not bug I can't understand, that is why I ask your help maybe you can help me to understand either it is bug in FIORI elements or I did something wrong in my application.

So I describe my problem

I created a very simple 2 level RAP application with header and items

On item level application contains field "Field1' which could be filled by using value help which I defined as list box via annotations

@ObjectModel.dataCategory: #VALUE_HELP
@ObjectModel.representativeKey: 'ProductClassId'
@ObjectModel.resultSet.sizeCategory: #XS

Everything is fine when I create a new record the first time I can choose the value from list and save,but if I tried to create the second line immediately after the first line, I can't because application gives me error message "Enter a value for the Field1 field" in that case front end even didn't request back end. In debug mode I didn't see any requests to backend.
I have to notice that field with value help is mandatory and key, oData version 2, managed without draft.
Is it bug in FIORI elements or I did something wrong in annotations of CDS views?
I will be very thankful for any help.