Radio field issue

Hi,
I have an issue with a radio field. There is a required radio field on the checkout page http://mydevserver.ru/checkout/ of my site. It has two options: option_1 and option_2. When a customer registers on checkout he selects option_1 for example. The registration is successful. But the value of radio field is not saved. The customer enters his account page http://mydevserver.ru/my-account/edit-address/billing/ and sees that nor option_1 nor oprion_2 is selected. The same picture he sees on checkout page trying to checkout the next order. He tries to edit this field on /my-account/edit-address/billing/ page. But he is successful only whit option_2 selected. If he selects option_1 on /my-account/edit-address/billing/ page he gets an error: this field is required. That is the selection of option_1 is interpreted as empty radio field.

Would you be so kind to help me with this issue?

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