I am seeing issues after upgrading to PB 5.5.6 when I try to import XML from a course. After choosing file, selecting all to import, and choosing import the page is simply reloading without attempting an import. Has anyone seen this issue before or is it known? Also on Wordpress 4.9.8 and PHP 7.1. Host is Pantheon. Here is a screenshot, and looks I believe as you would expect:
Note: I have indeed selected all chapters, etc to import before attempting the import.
Thanks for the help!