Dear All,
I'm experiencing the same error.
I have a data set with 3 sessions for each subject, but for some subjects, a session is missing.
I indicated 'allow missing data' at the 'set-up' condition tab, but was now wondering whether the imbalanced design could be related to the error message I get after the denoising (and prior to setting up the first-level analysis)?

Thank you for any input!
All best wishes,
Kaat