a few days ago we found out that we're no longer able to find messages with tags that have a hyphen "-" in them.
The Flowdock API also returns only an empty array  in response to such queries. For example, we have tagged messages with "feedback-fi" and "feedback" when I try to find messages with only "feedback", I also get messages tagged with "feedback-fi".
We rely a lot on these kinds of tags in our day-to-day workflow and them being broken is a really bad thing for us.
I created a support case for you on this issue and a Support Engineer will contact you via that case.
This is a known issue and is currently being investigated by the Engineering Team. When there is a disposition to the issue, we'll update here as well.
@Michael, do you have any update on this bug fix?
Search on Flowdock relies heavily on tags. Not being able to search tags that have hyphen is tantamount to Flowdock search not working. Please make this a high priority bug if it's not already.
Good news, its actually almost fixed, just needs a little bit more testing then it will be deployed, therefore, you can expect this soon. Sorry about the delay in responding and thank you so much for taking the time to report this.
The fix for this has been released. Please let us know if you are still seeing an issue with Search.
Thank you again for reporting this and your patience while it was being addressed.