i don't see an electrical difference between "how it is and does not work" and the seemingly working old setup.
your schematics do look right, though i wanted to start this answer with Holy crap that's a lot of sensors. i couldn't yet find a voltage dividing anything. you should check the voltage at your multi-socket with the sensors connected.
maybe it's just not enough current? are you able to disconnect single sensors? when does it work? you could roughly calculate the current flowing through each sensor for different situations (warm/cold for the temp sensors for example). the current from your arduino is limited of course, depending on your power source, imagine one million of your temp sensor circuits (including the 220 ohms pull up resistor)... each sub-circuit draws a maximum of 22mA... that would be a theoretical 22kA current, which could be considered a "short". ... just to illustrate the problem: your setup might be right, but just over the limits.
this of course does not explain why it worked before. maybe you changed the supply from USB to external?
// kuk