Interesting fact: If you take the raw file, and use import to database (importing the all file) then export to edf. it produce a very different file than exporting directly to edf. (300 Mb vs 600 mb)
“imported signal”
Raw signal
Edit: i forced the epoch size to be 250 here: brainstorm3/toolbox/io/out_fopen.m at master · brainstorm-tools/brainstorm3 · GitHub and it seems to be creating a correct file. By default Brainstorm was trying 1000.
so my guess would be that the issue is in EpochSize = bst_process('GetDefaultEpochSize', sFileIn);
it seems to be the same issue as in [EDf export] different result between continious file and imported epoch (it seems i forgot to reply back then; sorry )