Before anything, double-click on the colorbar of the figure, to reset the color bar parameters.
https://neuroimage.usc.edu/brainstorm/Tutorials/Colormaps
The “Invalid scale” label appears as it was not possible to find an adequate scale for the data. It could be that all the test results a p-value larger than the threshold, so there is not data to show (impossible to scale). Some of the things you can do:
- If your statistics are time-resolved, try to plot also the time series, and set the marker to a point where there is statistically significant results. For example (a figure from the tutorial mentioned in the previous post). As you can (hardly) see the sensor caps from 50 and 100ms are all white and show Invalid scale as there are no values to plot.
- Change the Significance level α in the Stat tab, so modify the data that is plotted.
Check this other post: Statistic for EEG source analysis: t-test