Declining one instance of a recurring meeting

I have just started with a new company and have heard a few user complaints about the inability to decline only one/few instance(s) of a recurring meeting. I’m pretty sure I’ve done that before in other companies. And when I researched the issue, it appears the option has been available for quite some time (at least back to 6.5?). So I’m guessing it must just be some configuration setting that’s incorrect here. Can anyone point me where to look to fix this problem?

Thanks so much!

Jackie