Description of problem:
This is extremely similar to BZ #1513327 but I'm seeing it on 6.4.0. Problem description is the exact same but I'm adding possibly relevant information:

I was trying to create a host on a VMware hypervisor using bootdisk provisioning method from webUI. I associated all required fields and simply selected the "Boot disk based" provisioning method. All other fields on "operating system" tab appeared the same as for "network based".

Under "Media selection", "Synced contents" was selected and Kickstart media was auto populated with RHEL Server 7.6 x86_64 Kickstart. The moment I submitted the create host form, the webUI raised an error on Media under "operating system" tab: 

Media can't be blank

And at the same time it switched the radio button from "Synced contents" to "All Media". I clicked "Synced contents" back, and RHEL Server 7.6 x86_64 Kickstart was automatically selected again on the drop-down. But once I clicked Submit, it failed again with the same "Media can't be blank" message.

Note that this is using a Host Group that's pointing specifically to this RHEL 7.6 Kickstart repo.


Version-Release number of selected component (if applicable):
Satellite 6.4.0.
tfm-rubygem-foreman_bootdisk-12.0.0-1.el7sat.noarch

How reproducible:
Every time.

Steps to Reproduce:
1. Create a Host Group pointing to a VMware compute resource and with RHEL 7.6 Kickstart.
2. Browse to Hosts > Create Host, select the described Host Group.
3. Click the Operating System tab, select Provisioning Method: Boot disk based, click Submit.

Actual results:
The webUI does not submit the command, stating "Medium can't be blank" instead.

Expected results:
The webUI should submit the command, and the VM should be provisioned with the Boot disk method.

Additional info:
The attachments from BZ #1513327 reflect exactly what I'm seeing. https://bugzilla.redhat.com/attachment.cgi?id=1352438 and https://bugzilla.redhat.com/attachment.cgi?id=1352441