Missing input options for datestamp

The select options only show up when you use a date_select widget. If you use a textfield widget, there is no need for that setting. It has nothing to do with the date type, it is the widget that matters.

Also, if you set a field up with the textfield widget, then decide to change it to a select, you won't see the increment option until you save the new setting.

The last possibility, the increment setting is in a collapsed fieldset, so you may be just looking past it. I put in those collapsed fieldsets to make the settings form less complicated, but people are missing important features so I am re-thinking that. In the very latest 5.1 dev version in the 5.x branch and in the 5.2 version I'm working on in HEAD I expose those options instead of hiding them.