Error due to date format change

[SHWA]

Hello.
By user request, changed the system property glide.sys.date_format value to "yyyy/MM/dd (E)" so that the day of the week is displayed in the date format.
It came to be displayed as expected, but when I entered the value of the Date/Time field when creating a record from the portal form, even if I clicked the Save button, the field was not updated, and it was empty or the previous value will remain.
Anyone know how to get around this?

Thank you.

[SHWA]

Hi @OlaN 
I set it to yyyy-MM-dd E.
I can now save the Date/Time field as well, but the time became 00:00:00.
Even if you correct the time and save it, it will return to 00:00:00...

[OlaN]

Do you have any client scripts running that validates or clears the time?

The setting of a time should not be affected by the date-format parameter.

[SHWA]

This error occurred in the OOTB Announcement table.
There was no client script related to dates as far as I could see.
I thought it might be related to the business rule "Announcements To/From Date Validation", so I tried deactivating it, but the time is still set back to 00:00:00.
I also tried it with Date/Field fields from other tables, but the same thing happened.
in the portal?