Hi,
There should have been no changes to the BDT output that I am aware of in the latest release. For the correlation matrix, there might was a change to the options (to allow omitting the printing of it during data loading, maybe this is related).
I’ll look into the missing correlation matrix, but for the totally different and wrong resutls of grandient boosted DT’s I need some more information 
EDIT: Could this topic be related to the unexpected output that you see? Change in TMVA::BDTG results
Cheers,
Kim