This is likely because Company is a link from post. One way to resolve this is to store companyID as a top-level field on the Post (alongside Company if you need that too).
Then, you can change your query to be companyID == $0
This is likely because Company is a link from post. One way to resolve this is to store companyID as a top-level field on the Post (alongside Company if you need that too).
Then, you can change your query to be companyID == $0