Page caching in XenForo will prevent any changes made by an add-on from being reflected on guest pages if the changes depend on dynamic logic, such as a session key for guests being incremented.
When page cache is enabled, XenForo serves fully cached versions of guest pages without executing most of the PHP backend logic, including add-on code or session handling. This means:
If an add-on modifies the page dynamically based on a session key or other guest-specific conditions, those modifications will not occur because the cached page bypasses the logic responsible for generating them.
The cached page is static, so any session key increment or other changes will only be reflected after the cache for that page expires or is cleared.