First date field not saved

I have this setup:

Multiple fields table:
field_group_multiple_table: open
required_fields: yes
parent_format_type: Div
show_label: yes
label_element: Header 3
effect: none
speed: none

In this group I have two text fields (both are working fine) and one date field. All are set to unlimited values and required.
No matter which date field wigdet I select (tested with date_select, date_text and date_popup), the 1st date value is not saved.
I was looking in database, but there was no record neither. Other date values (2nd and all following) are saved and displayed OK.
Date fied is collecting only year, month and day.