The reason you are not able to view the POAP collection in your wallet is because most wallets are currently unable to natively display POAPs and many other NFTs due to their unique token addresses.
There is a workaround for this, with some wallets enabling you to add each individual POAP token address so that the wallet knows to display them and how to display them. The problem with that "fix" is that you would need to do this for each and every POAP your wallet holds and any future POAPs you collect as well.
To view your collection, simply visit POAP Scan and connect your wallet, or manually enter your Ethereum address, ENS name, or email address. The page that follows will allow you to see your collection that has already been minted to the blockchain (when inputting an Ethereum address), or has been reserved to mint to the blockchain in the case of an email address collection.
POAP Scan interface:
Better yet, we'd recommend downloading the POAP app (iOS/Android) to view your POAPs, as it is by far the easiest way to keep track of your collection. It also includes an additional way to collect POAPs that is only accessible via the app!
POAP app interface: