Following the direct realization and stabilization of that insight of anatta, the above actualization becomes a natural effortless state.

I have not experienced the slightest trace of subject/object duality and agent-agency for the past 10+ years.

For example even after it is seen that everything is a manifestation of awareness or mind, there might still be subtle tendencies to reference back to a source, awareness or mind and therefore the transience is not appreciated in full. Nondual is experienced but one sinks back into substantial nonduality - there is always a referencing back to a base, an "awareness" that is nevertheless inseparable from all phenomena.

If one arises the insight that our ideas of an unchanging source, awareness or mind is just another thought - that there is simply thought after thought, sight after sight, sound after sound, and there isn't an inherent or unchanging "awareness", "mind", "source". Non-dual becomes implicit and effortless when there is the realisation that what awareness, seeing, hearing really is, is just the seen... The heard... The transience... The transience itself rolls and knows, no knower or other "awareness" can be found. Like there is no river apart from flowing, no wind apart from blowing, each noun implies its verb... Similarly awareness is simply the process of knowing not separated from the known. Scenery sees, music hears. Because there is nothing unchanging, independent, ultimate apart from the transience, there is no more sinking back to a source and instead there is full comfort resting as the transience itself.

Lastly do continue practicing the intensity of luminosity... When looking at tennis ball just sense the tennis ball fully.... Without thinking of a source, background, observer, self. Just the tennis ball as a luminous light. When breathing... Just the breathe... When seeing scenery, just sights, shapes and colours - intensely luminous and vivid without an agent or observer. When hearing music... Sound of bird chirping, the crickets… Just that - chirp chirp. A zen master noted upon his awakening... When I am hearing the bell ringing, there is no I and no bell... Just the ringing. The direct experiencing of no-mind and intensity of luminosity.. This is the purpose of the practice of the four foundations of mindfulness that is taught by the Buddha.” - Soh, 2011

When anatta is realised, there will no more questioning about a “who” just like when santa claus is realised to be false, there will be no more questioning “where is the santa claus”. The entire question is just absurd and silly. Only conventionally do we talk about selves for mere convenience.

If it is "always the case", why can't we see it?

How can you see the "truth"?

But i generally advise people to start from realising I AM Presence first.

The real illusion is the one pointing to William, for he feels to be the real subject able to see the person.

Yes the point is not that everyone has realised this truth. But the point is to distinguish between a momentary peak experience of no mind and realizing anatta as the seal that is always already so, which brings no mind to its peak and matured natural state of effortlessness.

There is indeed a big difference between realising and not realising anatta. Directly realising and actualizing it puts an end to afflictions and sufferings.

For example:

“Though anatta is a seal [Soh: i.e. a truth that is always already so, pertaining to the nature of mind/experience], it also requires one to arise the insight to feel liberated. When a practitioner realizes the anatta nature of manifestation, at that moment without the sense of observer, there is no negative emotions. There is only vivid sensation of all the arising as presence. When you are angry, it is a split. When you realized its anatta nature, there is just vivid clarity of all the bodily sensations. Even when there is an arising thought of something bad, it dissolves with no involvement in the content [Soh: i.e. mental contents like stories, imagination and conceptualization along with emotional involvement]. To be angry, a 'someone' must come into the content. When there is no involvement of the extra agent, there is only recoiling and self liberations. One should differentiate arising thought from the active involvement of the content a practitioner that realizes anatta is only involved fully in the vivid presence of the action, phenomena but not getting lost in content.” - John Tan, 2009

“Not creating an idea of a self frees us completely from anger. You cannot have anger unless there is a self. There is no boundless and omniscient self somewhere in the sky that created the whole universe, and there is no tangible and limited self that inhabits this bag of skin. All of reality is simply infinite dharmas that arise and disappear in accord with the laws of karma. There is not one thing standing against another.” - Zen Master John Daido Loori

"...The anatta definitely severed many emotional afflictions, for the most part I don't have negative emotions anymore. And either the anatta or the strict shamatha training has resulted in stable shamatha where thoughts have little effect and are diminished by the force of clarity. I'm also able to control them, stopping them for any amount of desired time etc. But I understand that isn't what is important. Can I fully open to whatever arises I would say yes. I understand that every instance of experience is fully appearing to itself as the radiance of clarity, yet timelessly disjointed and unsubstantiated.." - Kyle Dixon, 2013

No, that is wrong. You do not understand Kyle’s insight and experience. But I feel it is pointless to continue this conversation with you.