I've had this from my summer grow.
Too low OF Rh And temps that go above 17c can cause this.
Try not let your RH/temp leave these ranges. And if you have grows going. Tru get them dried in next few months. Or arrange for some AC to run in a dark room for a few hrs..
So, RH THE IDEAL IS 59: but between 55-60 you'll get away with it.
At the max 18c. No direct sunlight. And if using synthetic nutrients make sure to flush that shit good.
There's different harvest methods also..
You can dry the plant in its sub for a bit then pull out when soil is dryish and bag and hang upside down whole. (Do a night. As if you leave with roots on your get your going again. Also don't wash soil off roots. This was the only way I could dry my other plants later in summer without getting that hay smell. I kept the RH little higher as the tenp was like 22c at times. Before leafs curl into bud if the leaf-calyx ratio is high. She'll be a nightmare to trim.
Also if you over dry dry some 2 way RH packs jars half full and it should bring some of that away. But took a 3 month cure to get rid of my plants chopped early and dried wrong. As soon as they dry they stink of hay within 4 days the weed smell does be gone. But again, Mine came back with boveda packs 63%Rh and took them out after a few weeks after I could feel tur dif and a long cure got rid.
Hope you get a better dry this time.