I can understand your problem.Also it is happening with me also.But once the sdk will be updated you will not need to worry for 5months 6months or more. So as of Know you have to accept the loss. For 28days earning on Facebook audience network may be 15$-20$.So For know focus on content and app building and once we update the sdk you can update your app with it. Till that please have patience. Also if you want to
reduce your loss you can use this extensive
==Edit by Mod: Please don’t post direct extensions if it’s not yours, provide a link for the extension instead.==
and create an option like (Donation or Buy me a coffee like that. Hope you are satisfied