When running a constituent query the Prospect manager will show the correct start date for a Prospect plan. When running this as an Interaction query and Export definition the same results may be blank or show the incorrect start dates.
The important part for this to make sure the query and the Export definition are set in the same way. If it is pulling the wrong dates check to see if the query has Constituents\Prospects\Prospect manager start date.
From here change the Export definition to match by doing these steps, 1. Click the plus sign by Constituent 2. Click on Prospect and in the Select fields area that shows up for this choice choose Prospect manager start date 3. On the Prospects choice form step 2, click the plus sign , click Prospect manger, then in Select fields choose name