Calculation based on “select” field from field group not showing correctly

Calculation field is not shown correctly on the front-end if the calculation is based on a “select” field from a field group. Only the first “select” field is included in the calculation, not the other ones.
In addition, the first “select” field is included in the calculation, even if the field group is not displayed if the visibility condition of the group is not met.

Note 1: The calculation field is correct in the submission list view, in the export CSV and in the notification emails.
Note 2: The calculation field is correct with a “number” field in a field group.
Note 3: The calculation field is correct with a “select” field outside a field group.