If I have a required custom field for a requirement that field is still blank when I import the requirement. I'd expect it to force me to select/enter a value, if it is required.

PractiTest vendor suggested to raise here:

Hello Narasimha,
Following my conversation with the Product Team.
The request to add a verification/error step in case of the Import Jira issue to Requirement is not a request for just an enhancement, but rather a request to change the current functionality.
If implemented, this change might affect many other customers, which do use the Jira integration with Mandatory fields on Requirement level.

Therefore, I'd recommend to leave a Feature Request on our Feedback Forum regarding this functionality and we can monitor whether this request will be promotes by other PractiTest users. You can do it here: https://practitest.uservoice.com/forums/27423-general