Its part of the experience as a bounty hunter. In my case, I have not been paid in half of the bounties I joined especially when I was new and joined any campaigns I find. But now im more particular in joining bounties and look deeply to the project and the team running it.
Yes you are right. To be honest I've aldo tried not being paid by the bounty campaign that I am joining. And as a matter of fact I felt so down that time because all my efforts are just useless.