Rebuild MPLAfter creating a backup of your Quicken data file … To rebuild the Memorized Payee List from existing transactions, click Tools, hold down Shift and CTRL, then click Memorized Payee List.
Problem: Empty MPL List View or only a few entries show but File Information shows many MPL entriesCheck the MPL view. Click on Options and make sure that there is NO checkmark on "Show locked items only"
THW-CA said: Experiencing the same issue and the provided Answer doesn't really explain.
Payees can be added manually:
New payees are also added when you create new transactions in the account register. You can turn off the auto-memorizing of new payees in the Quicken Preferences.