Been having this problem too and decided to try to run some debug on the widgets... heres the only error that I saw - but it will take some time to detangle. When sp_sourseware is enabled, while the widget *should* be scrolling, each move of the mouse throws the following error
TypeError: Result of expression 'this.helper.scrollParent' [undefined] is not a function.
Of course, I am having the same errors as others too - the plugin admin pages are working, the schedule and biblio pages are being created, the database is populated - but when it comes time to run schedule_page() -- crickets... nothing.
SO I wonder if the problem could be the js vm crashing silently? When it tries to parse the sp_sourseware under wpmu it fails and subsequently all of the other scripts do to? This is a longshot guess but since I couldn't find anyone posting the errors I thought I would give it a shot. I hope this thread is still being followed.