Can't 'accept' calendar invitations on iPhone

I can't seem to accept calendar invitations on my iPhone calendar. I get the invitation and can see it in the calendar but the only option I get is to 'delete' it. It stays greyed out. I have to actually accept it on my laptop and then it'll appear as having been accepted but I'm not able to do this from my phone (I used to be able to do it - I feel like this changed with one of the latest updates?). Also, to make things extra fun, if I change the original invitation and resend it to myself after editing it, I'm then able to accept it... Anyone find a workaround for this?