Summary: when trying to access a page that was previously denied by not being logged in, the page is denied(the "cached page" is shown).
how to reproduce:
1. without being logged in, try to access an acl denied page.
the "Permission Denied" page is shown.
i.e:
https://example.com/doku.php?id=namespacename:pagename
2. Click the "Login" button on the bottom right of the page
one will be redirected to the login page:
i.e:
https://example.com/doku.php?do=login§ok=6814a1d316888806a5678a50822a892a&id=namespacename%3Apagename
3. Fill in the form and click login.
one will be redirected "back" to the page:
https://example.com/doku.php?do=login§ok=6814a1d316888806a5678a50822a892a&id=namespacename3Apagename
but the page shown is the "Permission Denied" one.
Conclusing cache problem, avoid caching by purging:
4. Edit the address and add the purge=true.
the "correct" page will show up.
i.e
https://example.com/doku.php?purge=true&do=login§ok=6814a1d316888806a5678a50822a892a&id=namespacename%3Apagename