SOLVED (for me): The button to the left of the alignment choices had been switched somehow from "Align to Selection" to "Align to Key Object." When switched back to "...Selection" the alignment buttons worked as they previously had. I don't know if this switch was because of a random keystroke accidentally hitting an unknown hotkey or if the default state was changed somehow during an update, but this fixed my issue.
Ron
SOLVED (for me): The button to the left of the alignment choices had been switched somehow from "Align to Selection" to "Align to Key Object." When switched back to "...Selection" the alignment buttons worked as they previously had. I don't know if this switch was because of a random keystroke accidentally hitting an unknown hotkey or if the default state was changed somehow during an update, but this fixed my issue.