What gameplay feature is this bug affecting?
Breeding, studding and chasing

What's the issue? Please include any error messages you receive and as much detail as possible.
So with this particular lioness I'm unable to stud her normally, despite me having absolutely no ongoing stud requests. She does show up when I try to stud her to someone else, but it just says that she already has a request pending...which isn't true. And whenever I try to chase her, I only ever get a white error page that says "ERROR 50.7: Invalid user ID". She hunts normally but studding and chasing are a major issue.

EDIT: I've discovered another lioness with the same issue - except she isn't even eligible for studding, and doesnt show up despite being in heat and yet again having no visible stud request pending. It's as if she isn't in heat.

Any links relating to this bug? For example, if a particular lion is bugging, what is the link to that lion?
https://www.lioden.com/lion.php?id=794148650618 - the first lioness with this bug
https://www.lioden.com/lion.php?id=794145682905 - the second lioness I discovered to have this bug

Any screenshots you can provide us with?
Unfortunately I'm on mobile

Please provide us with step by step explanation how this bug happened so we can attempt to replicate it. If it's complex, please include screenshots where possible:
What I think happened is that I had sent a stud request to a lion that either got banned or deactivated and that's how it got stuck, then rather the game deleting the stud request, it got stuck and now they're both stuck and unable to breed.