In wp-admin, the date picker “calendar” shows in the bottom left corner when editing a post. Clicking on the date field removes it from the bottom corner and places it naturally.
I’m guessing it’s firing on the document load rather than selecting the input field.
Thanks for the post.
This issue would result from a jQuery conflict with one of the installed plugins or your current theme.
I would recommend you have a look at your console log for any errors that are reported on the page.