PDF/A conversion removes bookmark functionality

Hello,

For context: I am using a code I wrote in Python to automatically edit and merge PDFs. I've attempted to use Ghostscript to automate the PDF/A conversion as well, but found it was too unwieldy and bug-ridden to reliably convert, so the action wizard in Acrobat Pro is sufficient for my purposes.

When I attempt to convert a product PDF to PFD/A-2b using Preflight, I am able to create a compliant PDF/A-2b which verifies properly. The PDF/A also keeps my correct bookmarks in the navigation sidebar. However, clicking on the bookmarks in the PDF/A doesn't do anything. The bookmarks in the PDF behave appropriately, and I am able to jump around to each bookmark with no issues. The only reference to a bookmark issue in the Preflight report (attached) is "Repair invalid bookmark hierarchies (1 object)." It appears this error report addresses "syntactical problems in the bookmark structure" but I can't find any other information on how to resolve this. It seems that Acrobat's solution to fixing a perceived bookmark error breaks the bookmarks. When I run the product PDF through a different converter, I am able to get a compliant PDF/A-2b that keeps bookmark functionality. I would much rather use Acrobat Pro since it has the Action Wizard and my organization already pays for it. Converting to other PDF/A standards results in the same issue.

Is there a solution for this?