Good Afternoon Salvatore.
And I managed to reproduce the same:
I saw that in usm_request_item_form table of database there are two rows:
custom_date (updated correctly), and custom_date_fdms$$ (which is not updated).
And accordingly, the SC-UI shows the date related to the UNchanged custom_date_fdms$$ then too.
Unless somebody else in the community can tel you(and me) how to resolve this, you might consider to open a standard Support Case for follow-up.
Thanks and kind regards, Louis van Amelsfort.