2.9: cannot deploy charm nor add-machine with centos8

Centos8 machines get stuck in pending. Juju can create them, however the agents never get installed. This does not happen with centos7.

ami-0d6e9a57f6259ba3a does have cloud-init in the image.

$ juju metadata add-image --series centos8 ami-0d6e9a57f6259ba3a
$ juju deploy ./tests/suites/deploy/charms/centos-dummy-sink --series centos8 --constraints root-disk=10G
$ juju status
Model Controller Cloud/Region Version SLA Timestamp
test-deploy-centos8 test-centos aws/us-east-1 2.9.3 unsupported 16:26:27Z

App Version Status Scale Charm Store Channel Rev OS Message
dummy-sink waiting 0/1 dummy-sink local 0 centos waiting for machine

Unit Workload Agent Machine Public address Ports Message
dummy-sink/0 waiting allocating 0 54.172.49.90 waiting for machine

Machine State DNS Inst id Series AZ Message
0 pending 54.172.49.90 i-0c3d00e7486d4b559 centos8 us-east-1a running

$ juju add-machine --series centos8 --constraints root-disk=10G <-- same result as above.

$ juju add-machine ssh:centos@x.x.x.x <-- hangs