This is something I'm still testing, so take it with a bucket of salt, but I've found that exposing myself to very strong samples of things that I was unable to smell made something click again and I started to smell them again. Seems like something in there needs to be retrained to odors.

I'm convinced that over the decades we'll continue to be a little surprised but just how much of our body-machinery is doing jobs of self-calibration, regulation, and safety-interlocks.

That's the basic method of retraining. I've got a bunch of essential oils in tiny jars and I regularly take a 20 second sniff of each whilst thinking strongly about the smell in context. For example, when I smell the lavender oil I recall the garden at my grandma's house which obviously was full of lavender. It's definitely helping, but there are still a lot of gaps.

There has been promising work on olfactory training, which you can do very inexpensively at home. If you can, I would consider seeing any ENT first to rule out polyps, etc.

Thanks for the info. I'm on top of it (in the ways you described) but still appreciate it and maybe someone else will see your comment.

Good luck!