tried a few samples and it always worked for me in a content page or in full page.
Is you session manager defined in the content page or in the layout page?
Also is it on the top or nested somewhere? hope not in a modal or so
Last I remember, those don't work either for NodeJS.
Best option we have found so far, as suggested by Patrick, is to just create a auto-run flow/SC on the content page, as they are called every time a content page is loaded.
Confirming the AC Session Variable does not work for me either, in AC Session Storage Manager. This is only the case if the AC Session Storage Manager (or Local Storage) is applied to the content page. If I apply to Layout page it works.