We've seen the following problem a couple of times: after resetting scores to zero, the plugin no longer updates the scores. A build with no changes that would have been worth a single point, for example, now is worth zero points after performing the reset.
The problem may resolve itself after a Hudson/Jenkins restart, but I cannot confirm that, although the first time this happened the problem suddenly fixed itself, and I suspect it was due to a restart. The current occurrence has not yet been followed by a restart to verify that. If we do a restart and it suddenly starts working I will update this report.