Can’t Select “Monthly/Calendar View” in Full Calendar Skin

I’m trying to use the Monthly/Calendar View in the Full Calendar Skin, but when I have that skin selected, the Default View shows the Monthly/Calendar View as an option and loads a preview, but it’s greyed out and I can’t select it.

I’m not sharing a link because it’s a back end option I can see but not select and I have a different one on the front end for now. I like the fact that you can select “Weekly” or “Monthly” on the same page, but it only has Weekly, Daily and List since the Monthly isn’t available.

I was trying to figure out if it was a “pro” option or something, but I’m not finding that in the documentation.