I contacted Support yesterday with the same issue, and they had to raise it further to their Product and Development team.
I received the following response today, which worked:
"Here are steps to correct this:
1. Click Forms on the upper-right hand side
2. On left-hand side click on "Ownership % Wks"
3. Down at the bottom click on delete form
4. Click Yes
5. Now on the upper right-hand side click Step-by-Step
6. Now click on Business Info
7. Click Shareholder Information
And click Edit on the shareholder and the check mark should be gone."
Hope this helps!
