Hi @Eric503 ,
Regarding the configuration that you mentioned, I think it is correct. Currently, I could not reproduce your issue on my side. Please check if you have configured a Field-Level Access Permission in your CDS Entity, and you use the related field in the Condition component of your Business Rule.
If you have configured a Field-Level Access Permission in your CDS Entity, and you use the related field in the Condition component of your Business Rule, your Business Rule may not fire due t the Field-Level Permission limit. If it is, please consider remove the Field-Level permission from your CDS Entity, then try it again, check if the issue is fixed.
The following are some common issues about not firing Business Rule in Entity form:
https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/create-business-rules-recommendations-apply-logic-form#common-issues
If the issue still exists, please consider remove the Business Rule from your Entity, then re-create a new one for it, check if the issue is fixed.
Regards,