I am missing a cat on the hard level - Hit the hint button, Nothing happens, It's one of the special cats... I have 2 white buildings left, Is the cat invisible?

EDIT: After testing, bonus content for all games except HC in London is unlocked when special cats are found. Being online is not required. I suspect that HC London is not working correctly due to my being offline (which means that I never get Steam achievements). Devs, please fix HC in London so that the bonus content can be accessed by offline players. Thank you so much! I'll leave my initial post below. ====== Does the bonus content require being online for the unlock to actually work? ...

Ate to play on win 10 did not seem to find any problems. If there are problems with Normal mode on win 8.1: it is not passable, it writes about the arrival of a train with cats and problems with the menu begin (you can’t exit, restart, etc. Exit ONLY through a forced alt+f4 termination)....

I have 1 cat left which does not register when clicked. I am playing Advanced without using hints, the annoying thing is that I can see it!!! It is being held by the lady at the train station I have clicked on her from head to toe & then she disappears into the wall for a while after the train leaves before re-appearing. I have completed the side missions but not touched normal mode as I don't want to risk losing my progress in advanced. Out of desperation I checked on You Tube & the guy on there just hap...

Found all cats in Advanced: https://imgur.com/a/JtZDg3X Achievement did not unlock. I did use some hints. Last cat I found was Rita Oreo, if that matters.