In not too many words, nothing blocks presence.
I know that such a statement may not appear to be helpful, so let’s say some more.

What is presence?
It is not something that one does. It is not something that is achieved.
Presence is.

In Sanskrit, it is the term Sat in Sat-Chit-Ananda
Presence/Sat refers to reality. That which is and cannot not be.

What does presence have to do with you?
The question is, what ‘you’ are we speaking about? Which I are we speaking about?
Is I the body mind or is I that which is and knows that it is?

The scriptures say that there is only one Self, one I, and it is that which is and cannot not be. In other words, presence.

I is Presence.
What can block I? What can block presence?

Only the misunderstanding that I is something that can be blocked. Only the misunderstanding that I is an object, a form that exists in time and space , which can somehow be blocked.

What blocks presence is the misunderstanding about the Self, the misunderstanding about yourself.