I have no experience with the vacuum ovens or BHO really. I have been making oil consistently for about 4 years now. That is all I consume pretty much, don't care much for smoke.
I had something similar happen to me for the first time. I think I may know why in my case. Maybe your case is similar.
What time of year did you do your other extractions without a problem? The reason why I as is I don't do many extractions during the summer. In the past it was because I didn't want any bugs getting into my RSO, not to mention all of the birds an other critters running around my yard. (You would have to see it to believe it). Anyway, I just did a QWET extraction, I have only done a few in the past without any problems. Same strains, same process, but something was much different this time. I couldn't get rid of the water. Normally the water evaporates pretty much with the alcohol. My more dirty batch, I decided to put on some light heat like I do for the final purge of RSO, but still, could not evaporate the water. By the time I could get rid of the water, the end product looked awful. Never happened before. There is one difference that I am aware of. The weather is hot and very humid. The other times I did QWET extractions my house was very dry because I did it in the winter. I use wood burning stoves to heat my house, so it gets very dry. I used 190 Everclear for the solvent. No with 99% iso, any time of year, I don't have a problem. There is a lot more water in the 190 compared to the 99% iso. Unless of course the alcohol was mislabeled and was only 151 or something. ??? Maybe it is due to the high humidity. I am guessing that is what my problem was. I will not do another QWET extraction during the summer!! Maybe I will never know the answer, but I don't have time for crappy oil.
Let me know if you believe it could be the time of year compared to your other extractions. I realize you are using an oven, but I also tried using heat with my lower grade batch and go the same results. I wish I knew if it was the time of year or I got ripped off on my alcohol.
To whoever on page 1 that asked about my method of winterizing, did I use heat? No, I did not use heat, that is not why the flavors disappeared. I am 100% confident that winterizing removed the flavanoids from my oil. The reason why we are not all in agreement on this, in my opinion, is because a lower grade oil being winterized will in fact probably improve the taste. However, when you have a virgin oil that is already elite, and tasty, you winterize it, kiss the nice flavors good buy. Every time I winterize, I can confirm it. I have been working with the same strains for over 10 years, only making oil for 4 though.