Emoji sync across devices

I used to be able to use emoji characters in iCal descriptions, and they would sync across devices and computers via iCloud. They no longer sync, instead a question mark in a box appears where the emoji character was on the device used to input the character. This is now the case between iOS and OS devices, though just last week, the characters would sync fine if originally inputed on an OSX computer (showing up on iPad, iPhone and other Macs fine). Any others experiencing this problem?