iPhone wallet: Latest transactions delayed

Hi, usually when I use the card in my wallet to pay I get a notification about the transaction straight away but lately this seems to be delayed and whenever I make a payment I will get a notification for the previous payment I make. I just checked the latest transactions in the wallet and the last one is missing. Judging from what's been happening this will only show when I make another payment, but then the new payment will be missing/delayed. Any idea how to fix this? Thanks I’m advance!