When I post a Sales Deposit to match a Bank transaction, it no longer "matches"? It looks like no relationship exists between the them?

Welcome to the Community, @michaelrcorbett.

Let's ensure to choose the correct date and filters. This way, we can easily find the match for your bank transactions. Here's how:

1. Go to the Banking menu, and then select the For Review tab.
2. Click the calendar icon  drop-down ▼ to choose the date you want, and then tap Apply.
3. Select the filter icon  drop-down ▼ to pick the transactions you'd like to show, and then hit Apply.
   
   
   
   
4. Click the transaction to find a match. If the invoice is paid, let's locate the invoice payment. If not, we can look for an open invoice.
5. Select the Find Match button, and then pick all the matched transactions.
6. Also, if the sales deposit was created within QuickBooks Online, make sure that the account is correct. You can click the Categorize option and then select an account.
7. Hit Save once done.
   
   
   

Check out this article for more info about matching and categorizing transactions in QuickBooks Online: Categorize and match transactions.

Then, you'll want to reconcile your account to make sure your books are accurate. Here's an article for the details: Reconcile an account.

Please let me know if you have more questions about managing your bank transactions or anything else related to QuickBooks. I'll be here to lend a hand. Take care and stay safe always.