I notice that when I categorize a particular transaction, it no longer appears on my bank reconciliation, but the same is not true for the other way around.

There are many differences between reconciling and categorizing bank transactions, kogawa. I'll share what's keeping those two process connected.

The Cleared (C) status appears in your register after categorizing bank transactions. Meanwhile, only the transactions with Cleared (C) and blank statuses appear when reconciling an account.

When reconciling an account, you can set filters to easily look for the transactions. It is possible that you have set them differently causing transactions to disappear. Let's go back to your Reconcile page and click Clear filter / View all. This will display all unreconciled transactions of the affected account. I've added a screenshot for your reference. 

We can also press the Filter menu (funnel icon). We'll be able to properly set the page for the transactions you want to appear.

On the other hand, are you looking for ways to take your QuickBooks experience to the next level? I'm excited to share that you can connect with our QuickBooks Live Expert Assisted team. They are here to help you manage your transactions and ensure the data integrity of your account. Let us support you on your journey to financial success.

Furthermore, we can proceed with reconciling the account after we set the filters. Then, we'll be able to close your books.

Keep us posted if you have additional queries with handling your bank transactions.