What can I do if an application isn’t working After The update to iOS 12?

I‘ve a problem with Kik app, after the update to iOS 12, I can’t Video chat with my data plan but only when I’m in wi-fi connection. The video chat begins to work but after 5 seconds the app closes. I tried all the passagges on the support Apple and Kik support. But the video chat still not work. I updated the app at The last version but without success.