Sorry for the long wait. This patch should fix the problem: https://github.com/pkp/omp/commit/8b316 ... e2ebf.diff
It's also listed as a OMP recommended patch, here: http://pkp.sfu.ca/wiki/index.php?title= ... es#Patches
It turns out that I was testing only with my own working copy of the system, and it had exactly the folder it was missing. That's why it was always working for me.
The usage event log files will also start to be processed now (you might have to wait for the next day to see some statistics inside the reports). Let me know if you have any other problems.
Thanks and sorry again for all the trouble,