(always appears along with laziness, elation/depression, shamelessness and lack of faith)

What is lack of intrinsic awareness? It is a lack of being aware to one's fullest capacity and it covers the three realms of life. Its function is to serve as a basis for mistaken stubbornness, doubt and emotionality about the entities of reality.
This unknowing is a mental event that is confused about reality as it is.

This lack of intrinsic awareness is a confusedness and a pervertedness. Regarding this state of confusedness, the Acarya Vasubandhu, in his Pancaskandhaprakarana, is of the same opinion as and agrees with the statement of his brother, Asanga, in the Abhidarmasamuccaya. Dharmakirti, however, talks about pervertedness. Although lack of intrinsic awareness consists of two aspects -- confusedness and pervertedness -- all authors agree that the main counteragent is discriminative awareness which understands the fact that nothing has an abiding principle.

Lack of intrinsic awarenss is twofold:

1.    Confusedness about the relationship between one's action and its result
2.    Confusedness about the ultimate
The former accumulates actions that will lead to rebirth in evil existences, and the latter accumulates actions that make us continue in happy existence.

The statement that its function is to serve as the basis for mistaken stubbornness, doubt and emotionality means that, on the basis of unknowing, all other emotions come into existence. On this basis actions are produced, and on the basis of these actions the misery and frustration of samsara come about, so that all of the emotions and all evil depends on the lack of intrinsic awareness. So also, it is said in the Pramanavartika,

He who sees a self is
Constantly attached to this ego.
Through this attachment, he craves for happiness and
This craving conceals all defects.
All evils derive from nihilistic views.
This is unknowing and from that comes attachment.
And from that, anger and all the rest arise. By that alone
The cause of evil is explained as 'deludedness'.
Every instance of evil clings to the root of that (unknowing).
It also a view concerned only with what cannot last.
The reverend teacher (Tsong-kha-pa) says,
The root of whatever one may gain in this world
Is unkowing. Having seen this, and (then)
Reversing the order is
Said to be dependent origination (pratityasamutpada)
In brief, lack of intrinsic awareness is mentioned as the first member of the twelvefold chain of interdependent origination because it is the root of wandering about in samsara and the foundation of all actions and emotions.