I am also experiencing this issue. I have tried Chrome, FireFox, and Safari on a MacBook Pro as well as Chrome on an Asus running Ubuntu 15.10.
Has there been any further development here? I just found CalendarBudget and really like it but not being able to reconcile is a deal breaker.
Please let me know if I can assist troubleshooting this issue.
Watching the console in Chrome while attempting to drag and drop I do see an “Uncaught URIError: URI malformed” message. The number of instances of this error increase as I attempt to drag. I can provide screenshots if that helps.