Bryan,

From the rest of my abbreviated notes on this article, the author continues:

".....Col Lyles was cordially disliked due to his heavy hand of command. His letters show him to be an alarmist. He misunderstood the independent nature of Arkansas soldiers.....for mutinous conduct....At its worst, these troubles involved only 2 of 8 Arkansas units, leading to many desertions.....
The soldiers did not want to leave the lines they had worked on so hard...to be sent to another area..." [and appraently refused to report for duty as a result]...

The returns I have seen for May 2-July 8, 1863, indicate that the 23rd Arkansas was in Beall's Center, while the 18th Arkansas was in Steedman's Left Wing defenses. So it would seem that the 2 regiments were split up sometime during this period.

Sure hope I'm able to find those letters of Colonel Lyles--one of these days.