After adding a manual account, add at least 3 (dummy) transactions - e.g.: 2 non-split transactions and one split transaction. Enter the same text (longer than 30 characters) to the memo field for 1 of the non-split transactions, and to the memo field for 1 split entry of the split transaction. Leave the memo field for the 2nd non-split transaction blank. Then, proceed to search the last word of the text you entered in the memo fields to see if you are experiencing the same problem in this test file. If the search works successfully; only the 2 transactions (1 split and 1 non-split) with memo field entries should show, and the transaction with no memo field should not show.
From there, you can then switch back to your original file.
Follow the steps below to switch files:
Quicken will list the most recently opened data files, with a checkmark next to the file you are currently viewing.
Let us know how it goes!