Why all of a sudden, distributions not showing as income on income/expense report

This is bit difficult to understand.

The combination of "Taxable distributions and SocSec from my spouse's show correctly" along with "the accounts that show correctly are unselected in the Customize Accounts- Investing selection" leads me to believe that those Investment Accounts are not selected to "feed" information to the report, (i.e., dividends and other income inside those Accounts don't show in the report, by design), but you have the report set up to show cash transfers out of those Accounts as a form of "Income" shown as "From {Name of Investment Account]" because you have those Investment Accounts selected as "Categories" in the Customization selection.

Is that correct?

I too don't understand "my account doesn't show if it is selected or not." If an Account is selected there's a check mark next to its name and if it's not selected there's no check mark. That should be very clear.

If my guess that you have the report set up to show selected transfers from the Investment Accounts as income is correct then I might review the Customization selections carefully. Something might have got changed in that area.

If you don't want an Account's internal activity showing up on a report you don't select it in the "Accounts" customization tab but you do want distributions out of that Account to show up as a form of income you would select it in the "Category" tab, and set up Transfers as either Exclude Self-Transfers or Exclude Internal.