We have three indoor cats.  We have four litterboxes for them.  We
used to use a clay-type litter designed for multiple cats, but
recently we changed to Fresh Step because it seems to control odour a
bit better.

Two of our cats have continued to use the litterboxes as before, with
no problems whatsoever.

However, one of the cats has begun urinating outside of the
litterboxes.  WE HAVE TAKEN THIS CAT AND HAD HIM CHECKED FOR URINARY
TRACT INFECTION IN THE PAST TWO WEEKS -- IN FACT, WE WENT TO TWO
DIFFERENT VETS, AND BOTH OF THEM GAVE HIM A COMPLETELY CLEAN BILL OF
HEALTH.

This cat still uses the litterbox to defecate, but he simply won't
urinate in the box; instead, he goes right up BESIDE the boxes and
urinates on the floor.

The cat in question usually urinates first thing in the morning when
we get up.  SO...we have tried closing the cat in one of our bathrooms
with a litterbox filled with the new litter.  We only leave him in
there for about an hour.  WITHOUT FAIL, the cat will urinate INSIDE
the litterbox when we do this.  But he simply WILL NOT urinate in the
litterbox under the usual circumstances -- circumstances where he had
no problems before.

My question is this: Assuming that there are no health issues, is it
possible for a cat to dislike a new brand of litter for URINATING but
not for defecating?

In other words, when a cat disapproves of a new type of litter, is it
common for her/him to still use the litter for everything except
urinating?

Another question: Why would the cat faithfully use the litterbox when
he is isolated with it, but NOT when the litterbox and the cat are in
the usual place?

We are changing two of the litterboxes back to the old litter to see
what happens, but I was curious about this nonetheless.

Any help or information will be much appreciated.