Upgrading ovn-chassis from 20.03 to 22.03 on focal randomly doesn't install ovn/openvswitch packages on units

Upgrading ovn-chassis from charmstore (rev 21) to charmhub --channel 22.03/stable (rev 118) 4 out of 3 out of 7 units were left with 20.03 ovn and 2.13 openvswitch packages, no matter that the apt source http://ubuntu-cloud.archive.canonical.com/ubuntu focal-updates/ovn-22.03/main was set.

Command used to upgrade the charms was:

cat >ovn-config.yaml<< EOL
ovn-chassis-sriov:
  ovn-source: cloud:focal-ovn-22.03
octavia-ovn-chassis:
  ovn-source: cloud:focal-ovn-22.03
EOL

juju upgrade-charm ovn-chassis-sriov --switch ch:ovn-chassis --channel 22.03/stable --config ovn-config.yaml
juju upgrade-charm octavia-ovn-chassis --switch ch:ovn-chassis --channel 22.03/stable --config ovn-config.yaml

octavia-ovn-chassis charm 3 out of 3 failed to upgrade, has to manually upgrade the packages on the failed units with:

juju run -u $UNIT "sudo apt-get install --upgrade ovn-central ovn-common openvswitch-common openvswitch-switch python3-openvswitch -y"