Shopify/Paypal Express Checkout First Order: Payment is pending

Hello

I started a shopify store and got a single order via paypal express checkout. In my shopify it says 1 order 1 unfulfilled order and it says: 'A $X USD payment is pending on PayPal Express Checkout.'

I logged into my stores paypal account and it says 0 transactions etc. I googled it and it said it might be due to being paid with an echeque? But I was worried I might've missed something when setting it up because it is my first order.

Any advice would be greatly appreciated, thanks.