What gameplay feature is this bug affecting?
Sorting for mut (cub)

What's the issue? Please include any error messages you receive and as much detail as possible.
None error messages but when I open in my den and sort it for muts he appears in like he should have mutation but he do not have mut he appears under his mother (fufy)

Any links relating to this bug? For example, if a particular lion is bugging, what is the link to that lion?
My lion overview https://www.lioden.com/lionoverview.php?id=440813&filter=mutations

The cub https://www.lioden.com/lion.php?id=794203770728

Not sure if it help but his mother (fufy)
https://www.lioden.com/lion.php?id=794203279581

Any screenshots you can provide us with?
Don't know how to provide screenshot sorry

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:
Just he born and I usually ignored him but I noticed he appears while opening lion overview and check "show lions with mutations only" he appears as having mut although he do not