Thanks for the kind offer to look into the "Like" button issue.
In order to try to facilitate that, I turned the feature back on, and this time it works. I have no idea what specific difference (now from then) is the reason, as too many steps of adjusting other aspects of my blog have happened for me to form a specific guess. I would suspect that the culprit was some other plugin that was deactivated during my site redesign/overhaul.
Thanks again!