I'm running Classic Business & Personal R62.16 on Windows 10 Enterprise. When I click "Change Assumptions" → "Investments" → "Edit" → "Show excluded account" in the Lifetime Planner, Quicken displays accounts I've marked "Hidden" in the Account List. After I exclude these accounts from the plan, they still show up in the list that appears after I click "Done".
I think it's problematic for the Lifetime Planner to offer to include hidden accounts, especially if they are also marked "Keep this account separate - account will be excluded from Quicken reports and features" in the Account List, as mine are. I think it's wrong for Lifetime Planner to show them as part of the plan after they've been marked "Exclude from plan" (Lifetime Planner does seem to exclude them).
I noticed this behavior today following an update. I am not sure if that's coincidence or causality.