An alternative for iotop until it is fixed is to install psutil at
https://slackware.pkgs.org/current/cinnamon-x86_64/psutil-5.9.4-x86_64-1_csb.txz.html
placing it in /boot/extras. Then
wget https://raw.githubusercontent.com/giampaolo/psutil/master/scripts/iotop.py
and store it either persistently or write a bash script on first array startup to download it. It is a clone of iotop using psutil. Then run it via `python3 iotop.py` or write a bash alias to run it.