Communication between the front end models and the framebuilder has been restored. I'm not sure exactly what the issue was, but rebuilding the framebuilder daqd executable and restarting seems to have fixed the issue.
I suspect that the problem might have had to do with how I left things after the last attempt to upgrade to RCG 2.4. Maybe the daqd that was running was linked against some library that I accidentally moved after starting the daqd process. It would have kept running fine as was, but if the process died and was attempted to be started again, it's broken linking might have kept it from running correctly. I don't have any other explanation.
It turns out this was not (best I can tell) related to the new year time sync issues that wer seen at the sites.