Ended up being the PHP Version we upgraded to in preparation for Moodle 2.5. We were using version 5.3.2 and I upgraded to 5.4.11 last weekend which caused this. I downgraded back to version 5.3.2 and stats re-appeared.
I did have developer on trying to figure out why it was doing it before I figured out that is was the php version. There were not any error messages or any extra messages that were showing up. I was boggled at why it was the PHP version too, everything else seemed to be fine.
It could have been the way I upgraded it on the cluster, I didn't do a purge or clean before updating to the latest PHP version.
I am going to try again before we make the move to 2.5 but this time I am going to do a full remove/purge/clean in apt of all PHP components than do a clean install.
Did the exact same thing again. This time I did a fully purge remove of all php components before I installed php 5.4.x . I had full debug mode on send to logs and tried to display on page. No errors at all in the logs or displayed on page. Is there anything else I should be doing? Is there anything in the /moodledata I should be clearing? I cleared PHP Cache and also tried to disable the opcode cache to see if it was that and still same results. This is bugging! We cannot seem to upgrade to latest because the current php version is 5.3.2 is the only one that shows the results correctly.
I am going to upgrade us to 2.4.+ since we can use PHP 5.3.2 with it and then try to upgrade PHP from there and see if the results are displayed correctly. Will be scheduled for next weekend so I will keep you updated.