Reminds me of my first experience. The trip involved getting something huge, like a big sense of "oh, I finally get it" but now, 3 years later, I'm still trying to figure out what I actually got.
What I got from LSD upon reflection was that my mental pre-processor (what assigns learned categorical and pattern information to incoming data) limits my perception, leading me to overlook important details about the new data, and causing me to lazily follow the same old thought patterns as if on rails. It's often necessary to ignore everything we think we know and look at our current situation with fresh eyes in order to progress.
Interestingly, this was the same reaction Aldous Huxley had to taking psychedelics. He wrote about the experience in "The Doors Of Perception", the book from which "The Doors" (band) got their name. I believe the quote originally comes from William Blake.
> “If the doors of perception were cleansed every thing would appear to man as it is, Infinite. For man has closed himself up, till he sees all things thro' narrow chinks of his cavern.”
Trauma and large life changes can also have a similar effect of reframing our views. Cognitive Behavioural Therapy is based around the idea of framing/context being important and largely habitual without applying concious effort
It's possible that certain insights, realizations, concepts, or thoughts are not easily transferable or translatable from one mind-state to another.
Also, selective amnesia is a common effect of various drugs, including high-dose LSD trips. Dreams are also easy to forget upon waking, leading some to recommend that you try to make what you do remember from dreams (and from trips) concrete in ordinary waking consciousness, through artifacts such as art, music, etc.
Some psychological theories posit that there is a mechanism of repression that occurs when the mind resists the brining of certain subconscious material to consciousness. This is one reason that some therapists recommend one does not venture too deeply in to the subconscious without a trained guide. You might not be ready to handle what you find on your own.
