Disk IO speed wrong

In the current version from the PPA, the disk IO speed is displayed incorrectly.
I am trying to measure /dev/md3, an MDADM RAID5 filesystem.
The current speeds according to the status bar: ◂19GB/s ▸7GB/s

apt-cache policy byobu
byobu:
  Installed: 5.12-0ubuntu1~ppa2
  Candidate: 5.12-0ubuntu1~ppa2
  Version table:
 *** 5.12-0ubuntu1~ppa2 0
        500 http://ppa.launchpad.net/byobu/ppa/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status
     2.68-0ubuntu1.2 0
        500 http://nl.archive.ubuntu.com/ubuntu/ lucid-updates/main Packages
     2.68-0ubuntu1 0
        500 http://nl.archive.ubuntu.com/ubuntu/ lucid/main Packages

sudo blkid |grep md3
/dev/md3: LABEL="data" UUID="0dfdd211-[snip]" TYPE="ext4"

~/.byobu/statusrc:
MONITORED_DISK=/dev/md3

cat /sys/block/md3/stat
  755992 0 116860162 0 282292 0 41830016 0 0 0 0

iostat -d -m -h
Linux 3.0.0-15-generic (desktop) 19-02-12 _x86_64_ (4 CPU)

Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sdb 0,83 0,09 0,04 14462 7229
sda 5,78 0,10 0,09 15654 14972
sdc 5,74 0,10 0,09 15651 14969
sdd 0,80 0,09 0,04 14484 7222
md0 13,36 0,01 0,05 2285 7684
md2 0,14 0,00 0,00 74 471
md1 0,00 0,00 0,00 0 0
md3 6,35 0,35 0,12 57060 20424