How long did you have it wrapped up for? You only need to wrap it when heavy frost is due, not all winter. Keeping it wrapped up all winter causes mould and rot...

This plant is commonly seen as a houseplant or conservatory tree in the UK - the RHS hardiness rating is 1, which means tender. I would not expect them to survive a winter outside.

Thank you both, we kept it covered all winter :(
Is there anything I can do to help the palm or is it too late as the centre looks mouldy...?