How to troubleshoot worker creation for OpenShift on OpenStack

Issue

OpenShift on OpenStack installation fails to create workers.

OpenShift cluster creation times out at:

[stack@undercloud-0 clouds]$ ./openshift-install create cluster --dir=install-config/ --log-level=info
INFO Consuming "Install Config" from target directory 
INFO Creating infrastructure resources...         
INFO Waiting up to 30m0s for the Kubernetes API at https://api.osc.redhat.local:6443... 
INFO API v1.14.6+17b1cc6 up                       
INFO Waiting up to 30m0s for bootstrapping to complete... 
INFO Destroying the bootstrap resources...        
INFO Waiting up to 30m0s for the cluster at https://api.osc.redhat.local:6443 to initialize... 

When checking created VMs, only the master nodes were created but no workers:

(overcloud) [stack@undercloud-0 clouds]$ 
(overcloud) [stack@undercloud-0 clouds]$ openstack server list
+--------------------------------------+--------------------+--------+-------------------------------------------------------------------------+-------+--------------+
| ID                                   | Name               | Status | Networks                                                                | Image | Flavor       |
+--------------------------------------+--------------------+--------+-------------------------------------------------------------------------+-------+--------------+
| 484b97fc-04b3-4a07-ba2d-95a5246fa44f | osc-c5r5c-master-2 | ACTIVE | osc-c5r5c-openshift=172.31.0.25                                         | rhcos | m1.openshift |
| b13018e2-c747-4643-9398-fd9e7c4fca70 | osc-c5r5c-master-1 | ACTIVE | osc-c5r5c-openshift=172.31.0.24                                         | rhcos | m1.openshift |
| c68ad2c9-1637-4dbf-872f-c9cd9afb2acd | osc-c5r5c-master-0 | ACTIVE | osc-c5r5c-openshift=172.31.0.15                                         | rhcos | m1.openshift |
+--------------------------------------+--------------------+--------+-------------------------------------------------------------------------+-------+--------------+

(overcloud) [stack@undercloud-0 clouds]$ oc get nodes
NAME                 STATUS   ROLES    AGE    VERSION
osc-c5r5c-master-0   Ready    master   4h2m   v1.14.6+888f9c630
osc-c5r5c-master-1   Ready    master   4h2m   v1.14.6+888f9c630
osc-c5r5c-master-2   Ready    master   4h2m   v1.14.6+888f9c630
(overcloud) [stack@undercloud-0 clouds]$

oc clusterversion seems stuck at 98% or 99% complete:

[stack@undercloud-0 clouds]$  oc get clusterversion
NAME      VERSION   AVAILABLE   PROGRESSING   SINCE   STATUS
version             False       True          24m     Working towards 4.2.10: 99% complete