Missing data in reports for current year



We have installed a Piwik instance late 2014 to monitor a single web site that receives a lot of traffic (hence why we decided to give it its own Piwik install). Reports for Day, Week and Month all work great. However, whenever we try to see the statistics for the current year (2015), it does not show anything. In the Visits over Time graph, we see the visits for 2014, but it falls to 0 visits for 2015, and all other graphs/widgets show “There is no data for this report”. The stats for 2014 are working correctly.

It really seems weird, considering if we switch the view over to monthly statistics for both January and February, everything appears as it should.
We run the archiving process as a cron job with specific periods to archive at appointed times with the --force-periods argument in the cron command, and separate logs for every period (for ease of debugging). When looking into the log file for the year reports, I see it does archive statistics for this year, as shown by the following excerpt in the log:
“Archived website id = 1, period = year, 3266223 visits in last last7 years, 1422604 visits this year”

However, it does not show up on the website.
Our other Piwik installation (which tracks a bunch of other websites) is working great and we can see the yearly statistics with no problem. They both have a similar configuration, so I’m at a loss as to what could cause this issue.
Does anyone have a clue as to what I could do to resolve this issue?