@Hi Stan,
i had the same issue and i followed your steps (DC offset remove,Normalize) so it is solved. I found out that Remove DC offset step does not affect the data. This is only performed for visualization purposes. I tried to remove DC offset with a FIR 1st order high-pass filter with 0.2Hz cut-off frequency to process the eeg data, as it is reccomended in other posts in the forum. After I processed the data without doing the remove DC offset step(fir instead), the signals are looking better than the ones in the beggining before doing any of the steps, but the AF4 channel(14th channel ) seems like doing a jump above the other channels.
When i am clicking Normalize after the FIR filter everything seems to be good! But is this the right way or should i perform some other step like the one with the fir filter for removing the DC offset?
Thank you
~Konstantina