The Reset button clears the value of hidden type input fields.

[axoide]

To prevent the Reset button from erasing the value of hidden type input fields before submitting the form, it is necessary to modify the jQuery code in the ResetButton Class (ViewComponents\ViewComponents\Component\ManagedList\ResetButton).
I propose to modify line #25 as follows:
--- . 'form.find("input:not([type=\'submit\']), select").val("");'
+++ . 'form.find("input:not([type=\'submit\'], [type=\'hidden\']), select").val("");'