If you are smoking the iso, you didnt do something right. One mason jar of MG 99.9% isopropy alcohol is completely evaporated out of a 14x9 pyrex dish in about 24 hrs. Leaving a white film that almost appears to be powder when scraped up. Without any sort of secondary purge.
The 96% ethanol will have 3.9% more impurities in it, some being water and the rest whatever else.
The isopropyl is still in your oil after 24 hours. I can promise you that and back it with CoAs.
Isopropyl alone, will evaporate completely over time at room temp. This is due to vapor pressure. The molecules are mostly free, some moving faster than others, making it possible for them to break the surface and escape. This will continue until the vapor pressure of the room and isopropyl are the same, or there is no more isopropyl left.
The molecules are no longer free once being used as a solvent. Therefore it will not act the same when attempting to recover or evaporate. Vacuum purging is an absolute must with all solvent, especially once with boiling points that high.