When donating to any cause - a nonprofit or a fundraiser - we can only change the totals once all the funds have been cleared.
While sometimes this is within minutes, other times it can take a few days.
If you have created a Better Giving account and have logged in, you can see any donations you have made that have not yet been cleared in your 'pending' page.
This is the same for donations to any fundraisers you may be donating to.
NOTE: you will only get a receipt once the donation has cleared.