I don't see any bug in there.
The first T-slide example is set to 2 semitones and when you expand the PB to 12 semitones the T-slide is still where you put it at 2 Semitones.
It is the pb range that has been higher since you expanded that range from 2 to 12
Example 2 is also correct since you have Made a T-Slide with 12 Semitones and then changed the PB Range down to 2 Semitones.
So there you have drawn the T-slide outside of the PB 2 Range.