Hello,
i reading your documentation and I see that digraph { … } macros not working, for ex. in this page: Class CKKSPackedEncoding — OpenFHE documentation (openfhe-development.readthedocs.io) is unable to show the block diagram.
Copy and past the code in the Graphviz Online is showed correctly.
I supposed that it a Issue on your site configuration for activate the graphviz plugin