The problem is, there are two keyboard settins. the one from gnome, just called "Keyboard", available in mint menu and synapse. But if you open cinnamon settings, in there you will find "Keyboard". You go in it and it's a "cinnamon settings - keyboard" you can have different shortcuts assigned to both. it's quite confusing.
Custom build w/ Gigabyte Z87MX-D3h | Intel Core i5 4670 | 8GB DD3 | 250GB SSD