I know how you feel, i had the same experience, and more than once. For those bounty projects i don't get my pay, my method was blacklisting the bounty manager, maybe some are not manager fault, but i still don't want to work with them. I don't give up too.
Great, this is one simple strategy that any bounty participant can implement for himself, because marking a manager who doesn't pay is a very good thing too, because once they don't pay, they will do it again in the future.
Maybe this can help a certain percentage of success for bounty hunters. But in fact, there are still many bounty managers who are well known for their many successful events, but on several occasions they also fail to pay bounty hunters. The prevention method by tagging several managers can be successful but is not completely guaranteed.