Since having upgraded from 2.7.0 to 2.9.1 (including an upgrade to PHP 5.5, thank you very much), Piwik is tracking between 0 and 2 orders per day even though there are many more being placed successfully. It worked fine before the upgrade. Visits are fine AFAICT though.
This is very strange, since it should either track all of them or none, right? How can this happen? Maybe something went wrong in the failed update to 2.9.1 when PHP hadn’t been upgraded yet? The files are exactly those from the downloaded .zip, but might the database be in a wrong state? The orders are being tracked through the PiwikTracker.php on the server side.
Any help would be very appreciated.