Hi @mubafzal2, the error that you report is expected due to a change in the data for the TF map from multitatper. Please update your Brainstorm instance to have this issue fixed.
More details: since the TF maps from multitaper are not "continuous" (same time definition as the sensor time series), in June 2024 (commit: 4b0d9782), we updated the TF structure for multitapers so they are time-band defined. So it is possible to plot them along side their time series, this was an error reported in the past.