iCal sync with iPhone5

I have an iPhone 5 and have had issues with iCal since upgrading to iOS7. My employer uses 7shifts, which has a link to sync to iCal. It has always worked in the past on my phone, but now it only shows up on my Mac Book Pro. At first, it just displayed old shedules - so I showed up for work early. Now it doesn't show my schedule at all.

I've gone to the calendar page on my phone and unchecked/checked the calendars, and dragged down in an attempt to refresh the calendar to no avail. I've copy and pasted the link from 7shifts again to make sure it's right.

Is there a way to force sync it? Plugging it in to my computer didn't fix it either.

Thanks!