Shift trajectory and average shift

Hello everyone,

I have a problem with my shifts study. When I compare my free spectrum with the one with my highest ligand concentration, I observe a significant number of shifts. But when I add a spectrum with an intermediate concentration to follow the trajectory of the shifts, a number of bars disappear from the plot as if the peaks were no longer shifting. I have not been able to find the cause of this.
I was also wondering if there is a built-in tool to calculate an average of the observed shifts to better select the significant shifts?

Thanks in advance