When attempting to edit firewall rules via VCSA on a specific esxi host, the "OK" button does not appear to confirm the changes. The "OK" button is hidden behind the rule list and is not visible so the changes cannot be activated.
Workaround#1 - if you know exactly what you want to set, it is possible to specify a filter to shorten the rules list, then the "OK" button will appear at the end of the list and you can confirm the changes.
Workaround#2 - edit the rules directly on the esxi host via its own webadmin in the Networking section / Firewall rules / Enable-Disable specific rule
So long, web management...
