Online Check in Broken

Trying to check in for my flight tomorrow. It requires the "Permanent Resident Card Number" field, even though I'm a US citizen, and have my passport information entered. Called Virgin, they said they just updated their system, and this is a bug. I'll have to check in at the airport...

Any risk in doing this? I already have my seat selected, etc. They won't give it away, right?

Sadly as others will tell you a seat selection is only a 'request' and not guaranteed! Even if you have booked and paid for a particular seat it can still be changed for "Operational reasons" !

More concerned about Online check in not working.

you will be fine as a selected seat should be ok but I would aim to get to the airport at the maximum possible time to check in to be sure.

I had a situation last December with the seating but was told by VS customer service and by VS ground staff in MCO DTDCI that seat requests now cannot be changed unless operational reasons and that it is not possible other than operational reasons for them to kick anyone out of their seat. Your seat selection should be good.