The bug is once you open diplomacy with a specific faction and add offers/demands, the final diplomacy value changes significantly and in a negative direction.

Example:
Relations with Faction X:
Positive Factors: +110
Negative Factors: -100
Total Relations: +10

Then you open diplomacy with them. As soon as you do something (add offers/demands), the numbers change:
Positive Factors: +110
Negative Factors: -100
Total Relations: -50

It is always a large change in a negative direction.

Does anyone know why this happens?