Hi Laurent,
for TPC we are using a bit different way of applying draw options to histograms. We have developed a small helper class, of which one function is called inside the initialize function of the QC task for each histogram. To set the colz option we then simply do:
histo.SetOption("colz");
For more details you can have a look at this post.
I just checked, with O2 and QC from today this version is (still) working, so there is no general issue in applying draw options to histograms, but it seems that somehow the setDefaultDrawOptions does not work.
Cheers,
Stefan