Book Permissions (only) nested in a subfolder

Hi, each of our Subsidiaries has a folder for its financial books in HFM. All employees of a Subsidiary are added to the Group "Sub Accounting". For each parent folder for the [Subsidiary's Books], we assign No Access to the Subsidiary Group and then provide explicit access to the 1 or 2 employees from that particular company. Hopefully, you are with me so far! Straightforward, I hope.

Now, for company X, there is a subfolder for the different branches of the company, let's call it Locations Books. In the folder Locations Books, there are some books (shocker!). So we have the same employees with explicit access to each of these Branch Books as we do at the Parent level folder, but for each of these Branch books, there is an employee unique to that branch that should also have access. So we explicitly provided access to those books for each supplemental user. However, our test user reported that they could not see their book.