Paired kittens being unpaired in cattery before having kittens

[Eurydice Barzane]

I've noticed this over the past few weeks. Kittens I have paired in cattery - and I know they have been paired because after partnering them it takes me straight to the 'pairs' section - are unpaired and back in their male or female groups.
I have unpacked a lot of cats recently, and pairing them as they were birthed was my way of keeping track of why I'd unpacked them.
If it had happened only once I would think it was a random glitch, but it's happened at least three times. I noticed it again tonight and had to re-partner kittens.
Has anyone else had this issue?
Thanks,
Eurydice