Hello Norman Diamond,
Thank you for returning to document how you resolved this. Restoring the Details tab to the specific columns you've relied on for years is exactly the kind of thing that's frustrating when an update quietly changes it, so it's good that you identified what happened.
Your diagnosis is accurate — the update reset your column selection and, in addition, set the column widths to 0, which is what made the list appear blank even though the processes were still present. Dragging the borders to widen them, then reselecting the columns you wanted, is the correct fix. One small shortcut for next time: right-clicking the column header lets you re-enable hidden columns directly, which can be faster than locating the drag point.
I appreciate you taking the time to write it up — a "completely blank Details tab" is alarming when you first see it, and this will help the next person who encounters it.