I recently changed my phone number on my credit card account. Should I wait 2-3 days before attempting a transfer?

I attempted a Money Transfer on the mobile app for credit card. But it was immediately declined on the app, without a 2 day period.

Is this an error?

It is money transfer of just 40% of my available credit.... £600 (avail. £1550)

Is it normal to need to wait several days for personal detail changes before attempting a money transfer?

Are there other reasons why I may be rejected?
I've made all payments on time and good credit score so not sure why it is rejected

Thanks