It sounds like a very common problem. With no background about the
specific situation, it's hard to say why the manager is reacting in
this way.
Of course we all know people are fearful of any change, generally. In
a case like this, I try to find out exactly what the person's real and
perceived problems are. Then, I try to align with his/her personal
goals. In one way or another, a lean transformation is likely to
address the manager's problems/goals. He/she may not be able to see
how this is so without guidance.
I can think of many possible contributing factors, and I can't guess
which ones are at play in your situation, or whether it is something
entirely different.
One factor is who initiated the consulting engagement?
If it was the same manager who is fearful of visualizing the process,
then it's possible he/she has realized the methods you are introducing
are more powerful than he/she had imagined, and might expose more than
was planned.
If the engagement was initiated by someone above the manager in the
formal hierarchy, then he/she may be playing along as a good corporate
citizen, but actually has reservations that have not been discussed
openly.
If the engagement was initiated by a peer of the manager or by someone
in a different department, then the fear may be that the other person
is trying to undermine the manager's position or credibility, to
position themselves for future advancement.
Another factor is the length of time the person has been in his/her
present position.
Assume the manager has been responsible for their department for more
than 4 or 5 years. If you demonstrate the possibility of 2x - 4x
process improvement, the manager will look good. They were smart
enough to engage you! If you demonstrate the possibility of 10x or
more improvement, they will look bad. How did they let the situation
get so bad during their tenure?
Assume the manager has inherited the process within the last 12
months. In this case, if they can achieve 10x or more improvement they
will look like a hero.
The visualization will make all of that very obvious. We often have to
tread carefully and be aware of who stands to gain or lose.