I have posted on both Zynga forums, submitted their google docs form, waited for weeks for a reply and all with no results. Meanwhile the bug report post has grown to over 200 comments of people having the same exact problem.
I noticed, among the comments, a moderator saying to send a DM on twitter and that's exactly what I tried.
I sent the following to @ZyngaSupport
"castleville, outranked/one up, can't summon dragon, can't defeat dragon supposedly already there. uid [uid]"
In less than 3 hours the issue was fixed!
I got my uid from this page.