Can you please confirm the exact setup of the plugin, all selected options? The code is set to show the session if it's an option which is added onto the html and not replaced.

I cannot replicate said issue.

Set ON - global config

plugin:

result:

Set off session:

result all need info:

Maybe replace: "Show Session Data" to "Show ONLY Session Data"

No, that's not the usage case here, it's an option and not Show only. Can you try viewing the backend in The English and saving? the plugin. What do you see below the plugin now with debug mode on?

It should look like:

In backend ALL - OK, i report about frontpage debug.

Frontpage:

SET ON - session data

Ok so the plugin is working on the backend. It also works fine on my frontend.

Can you confirm testing with the default Joomla! protostar template? Can you try testing on a fresh Joomla! Installation.

Tested on protostar - result same.

On fresh Joomla - not tested.

I cannot replicate on a fresh install.

Given it is happening on the frontend of your website, I suspect it's related to a 3rd party plugin.

Fresh J 3.7 - it's OK

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/15732

closed as no Core Issue. Feel free to reopen.