Hi Scott Miles
Thank you for reaching out to Microsoft Q&A
The Log analytics Primary key was not visible in Portal in Agents section for me as well.
As a workaround, you can use below Azure CLI command to fetch the Primary Key.
I have run this command in the Cloud Shell:
az monitor log-analytics workspace get-shared-keys \
--resource-group siliconfuncstrg \
--workspace-name valleylaw01 \
--query "primarySharedKey"
Output-