Input monitoring issues after Logic 10.7.5 upgrade

After automatic update, Logic 10.7.5 isn't working the same anymore. I can't monitor any of my tracks when trying to record. In older projects, I can hear everything that was previously recorded but if trying to overdub a track or creating a new track, i can't hear anything even though i can see the signal is being received. Another unexpected behavior is that when opening any of my previous projects, all audio tracks have the input monitoring automatically enabled... not just the track I have selected.