A question from a fellow grower:
I Am having some problems in my drying procedures.I have silver haze / purple haze / og k. They have a great aroma !!! Now after 2-3 days drying they are losing it. I have them in a nice size box with a few holes at top and bottom. They are in a lower room , Temps at 65-70 Degrees , with a humidity level at 50 % give or take 4 %. They are also in the dark ! I trimmed all larger leaves. Why am I losing aroma and gaining a hay or green smell ? This is not my 1rst time.
One thing you did not mention, was some air movement. You do not want a fan directly on the drying buds, but you do want air circulation.
As far as the smell; Probably due to drier herbs, not being as pungent as fresh herbs. The real question is: Are my buds still sticky? 
Our fellow grower says:
1 , I did leave out that they are drying in a large heavy duty refridg. box , theres no fan in the box! And yes they are still sticky. Like I said Its not my 1rst time. I am thinking it has some thing to do with there genetics ? My last run did not do this ! Nor the pryor 6, Seeds from another source