When I looked up constituents the revenue history shows that a portion of their membership purchase is going to a fundraising designation although the amount is actually zero. The only thing that these constituents have in common that they purchased admission tickets and put that amount toward a membership.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
Go to Memberships and click on the name of your membership program
Select the Rules tab and click Edit
Select "Yes, the tax deductible portion from benefits is contributed membership revenue"
Choose a designation and enter the percent as 100, then click Save
Select the Benefits tab and click Edit
Select "Yes, a portion is considered tax deductible"
Make sure that you have benefits with a value for your levels
In the Tax deductible amount field under one of the levels, enter any amount other than 0
Leave the Tax deductible amount field for at least one of the levels at 0, then Save
Go to Sales > Daily Sales and select a constituent
Click the Memberships button, choose that membership program, then select a level that you left the Tax deductible amount at 0 for
Add payment and complete the transaction
Search for and open the constituent record
Select their Revenue tab and the Revenue History subtab
Note that there is a donation line for $0 and note at the top of the constituent record that they now have the Donor constituency