Create Host Page Doesn't Finish Loading After Host Group is Selected

After upgrading Foreman and Katello to 3.2 and 4.4 respectively (following the instructions on the Katello upgrade page), the Create Host page on the web UI doesn’t finish loading when the Hostgroup is selected and parent hostgroup parameters are “imported”. The spinner at the top of the page keeps spinning.

Expected outcome:
“Create Host” page finishes loading and I am able to click on the “Submit” button to create the host.

Foreman and Proxy versions:

Foreman and Proxy plugin versions:
foreman-tasks - 6.0.1
foreman_ansible - 7.1.0
foreman_puppet - 3.0.6
foreman_remote_execution - 6.0.0
foreman_webhooks - 3.0.1
foreman_xen - 1.0.1
katello -

Distribution and version:
CentOS 8 Stream x86_64

Other relevant data:
Related: Compute Attributes disapeared after upgrade from 1.22 to 1.23

I’m almost positive the problem is with the upgrade process and its interaction with the foreman_xen plugin. The foreman_xen plugin works just fine when installed on a fresh Foreman installation, however, when an upgrade takes place something is broken. My guess is that something in the DB is nuked. Given that the spinner on the page keeps spinning and I guess this means Foreman is repeatedly trying to grab some data that’s missing, can anyone provide any guidance about how I can find out what data has gone missing after the upgrade? Like maybe there’s a way to “diff” the old database with the new one to find what’s changed post-upgrade or maybe the Foreman log-level should be increased to see what data Foreman is trying to grab but fails to?

I can grab foreman production logs and postgresql logs if required, however, a cursory glance shows no errors in any of the queries or renders after I select the Host Group.

To be clear, this only happens when attempting to create a virtual host using a Xen compute resource. If I try and create a bare metal host, the page will finish loading successfully.

After a handy error report (that I’d previously ignored in my initial troubleshooting) provided here, I was able to trace it to the deprecation of jquery numFields discussed here. Once I applied the patch located here, all is now well.