Sorry to bring this up again on the list, but unfortunately I could not solve the problem myself, maybe someone here has another idea? I have attached some more details of my analysis.

I am performing a longitudinal group-level resting-state analysis on 7 patients with left-sided cerebral tumors, before and after surgery. Each patient has 12 individually defined seeds (6 left-/6 right-sided). While most of the seed-to-voxel analysis worked fine, 4 out of 84 seeds (7*12) do not show a time-series in the single-subject analysis, sometimes only at one session. This concerns seeds on both hemispheres (also contralateral to surgery).

Preprocessing was CONN standard (including ART, but without slice timing). I have checked that all seeds are within the individual grey matter mask. I get a plausible value from the functional images at seed coordinates.

Could this be due to ART scrubbing?

I have attached an image of a missing time-series at one session.