Empty dates are save with negative value

I have a Repeatable fieldgroup with two fields of type date. It works well for some time, but if I remove the value of one date, the date will be saved with the value -0001-11-30 05:00:00 in the database. When I refresh the page, the value will be 2019-01-12 06:00. If I save it, the new value will stay. I can also change the new value, as long that it's not empty it will work.

After some testing, I figured that emptying a field should remove it from the database (in flexicontent_fields_item_relations) but for some reason when there's too much value to remove, an update with bad value is made.

Flexicontent (v3.3.1.5)
Joomla (3.9.6)

Hello

i have tested just now and i cannot replicate this

This should not be a problem in PHP code, fieldgroup will not save empty field values
instead it saves the values with a proper index skipping values that are empty

if you open browser console
is there a JS error during form loading or when you click form submit ?

Hello

hhmm testing more
i see that Joomla date picker element will auto fill
0000-00-00
when we click submit
so this will could be the problem

I'm using the option "use timezones" in the field setting. My Timezone is UTC -3.

In the database, the value is always saved in UTC 0 (I think), so it should have a line in php where they convert the UTC -3 to UTC 0. If this is the case, that could explain why the date is negative.

Also, this could mean the code is trying de subtract 3h from an impossible date and return something unexpected.