The compressor is turning off or is being turned off and you have replaced the most obvious suspects.
There are 2 thermisters part #21 & 21A shown in the Controls parts diagram.
You might want to test them with an Ohmmeter to make sure that they are OK. (disconnect the power from the fridge when you do this and disconnect the thermister(s) so that you are only measuring the actual component.
I don’t know what resistance measurement they have but perhaps once you know you could contact the supplier in the link above and ask them if it is the correct measurement or not. A thermister’s resistance value varies at a known rate with temperature and this feature is what is used to signal the control board as to what the “temperature” is in each of the two compartments.
My thinking on this is that if one of these were faulty it might be “telling” the control board that the set temperature is correct when obviously it is not and therefore to turn off the compressor.
According to the wiring schematic (as difficult as it is to view) it appears that one thermister is for the fridge and the other is for the freezer so it might be prudent to test both.
If they both are OK the problem might be the control board.