Hey there, @elizabeth-miller.
Congrats on making your first post here in the Community. Let's work together to see why you're unable to add so many invoices to transactions.
You should be able to match multiple invoices to a single bank transaction. However, what's the highest amount of invoices that you've been able to add to a transaction and successfully match them?
This additional information, will help me determine the best solution/answer for your business. I'll be waiting for your response!