Hi Stijn,
Unfortunately, as of this posting, this is a current known limitation. As we understand the issue, the issue is on Management Center itself, and not Reporter. For your reference, the reference number for this limitation is MC-1649. Look for that in future version release notes of Management Center to know when it is resolved.
Also, on a different note, just to make you aware - Reporter 10.3.x.x became end of support on March 5th of this year, and 10.4.x.x also went EOL last week. I would recommend making plans to upgrade to Report 10.5.x.x so you can be on a supported version. More on the Reporter EOL policy can be found here.
Hope this helps!