If you've recently renamed a package, then you'll have to reset your preferences so the app can find them again.
You will need to go to Preferences, which is located at the top right corner of your Flow screen, and then select Utilities, which is at the bottom of the list on left side.
Then, select Refresh Package Summary on the right side of the Utilities window
Finally, select Refresh All Assigned Packages on the left side of the Utilities window
Select Save, and you're done.