Soft-locked out of Riddler Mission: Cat woman riddle

[sed5000]

I did not solve the riddle "It doesn't take much to tame a cat, just make them wear this and call the bat" which requires a snapshot of catwoman wearing the collar. I finished the Riddler trials and catwoman left the building, and I cannot find her anymore, thus I cannot complete the riddle. There's no collar left as a item anywhere, and when I try to sleuth it out, it directs me to the opening challenge with the mirror reflection and spinning question mark. This is is already completed and cannot be interacted with, so the best I can get is a "solution partially detected."

Anyway around this? Or have I locked myself out of the final battle with Riddler. This is the only riddle I have left....

[MASTAN]

The collar lies somewhere on the ground inside that building. You just need to find it.

[Djozar]

Don't know. Never waited that long to do that particular puzzle. Always do it the first time I approach her in the Orphanage.

[chipperMDW]

It's still there. It's in the final exam room, near where you got the last key. She tossed it onto the floor as soon as she got it off.

[MASTAN]

I've just checked it and yes it's still there, near the lamp.
https://steamcommunity.com/sharedfiles/filedetails/?id=3106101072
https://steamcommunity.com/sharedfiles/filedetails/?id=3106100993

[sed5000]

Thanks folks, found it. Its irritatingly small and doesn't show in detective mode