I've looked into the session.io file and it has a bunch gibber and a message half way through indicating:
Session is not active
Cannot call default session handler ss
Parent session handler is not open
S SS and much more (not able to copy it out of Atom editor ....)
The result of phpinfo() call does not give a section labeled session as you've posted.
I'm running php7 (7.1.1-1) php-cgi (7.1.1) and php-mod-session (7.2.4-2). I've tried re-installing php7, php-cgi and php7-mod-session and rebooting, no luck. Tried removing and re-installing the above packages all with ver 7.2.9-3 and rebooting ... but then I get a browser error: Bad Gateway
The process did not produce any response.
Luckily, I have a firmware back-up on a USB stick so I can restore the Omega2+ to its previous working state (ie my php script is working but not the simple sessions script).
It appears I'm out of luck with PHP Sessions and the Omega .... I'll have to find another way to identify a user...
Thanks for the help,