I think the problem may be the new filesystem on the copied lv.
Here's what I did on a test filesystem and it worked fine:

1. Created new lv

Code:

# mklv -y lvcorenew -t jfs2 data2vg 32

2. changed new lv to be type 'copy'

Code:

# chlv -t copy lvcorenew

3. Ran cplv

Code:

# cplv -e lvcorenew -f lvcore

4. Created new jfs2log for the new lv

Code:

# mklv -y corelog -t jfs2log data2vg 1

5. Formated the new jfs2log

Code:

# logform /dev/corelog

6. Modified the existing filesystem to use the newly copied lv

Code:

# chfs -a dev=/dev/lvcorenew -a log=/dev/corelog /usr/local/corefiles

7. Mounted fs

Code:

# mount /usr/local/corefiles

8. Check filesystem

Code:

# ls /usr/local/corefiles