Can’t add bar code to wallet

I have an iPhone 14 Pro with IOS 17.5.1. My gym provides an iPhone app that presents a bar code. When the barcode is presented, there is a button at the bottom “Add to Apple Wallet”. When pressing this, a message pops up “Barcode not added. Please try again later.” I’ve tried numerous times over a period of weeks and always receive the same message. How can I add this barcode to Wallet? QR codes, as from airlines, save in Wallet fine.