Timecode set to 0 when making mxf

When I transcode a ProRes file to MXF (broadcast file) in Media Encoder I somehow loose the timecode of the original. It always starts at 0:00:00:00. I have not checked the 'start timecode at 0' checkbox in the render settings.

Usually this is not a problem, but now I need to make a MXF that starts at 10:00:00:00. When I render this to ProRes from AE and import it back again the timecode is correct. When I transcode this file to MXF in Media Encoder the start is set back to 0:00:00:00. 

Same thing happens when I do the render from AE straight to Media Encoder (Add to MediaEncoder Queue). Timeline is set to start at 10h, render when imported back again starts at 0h. 
In my settings I use a MXF OP1a wrapper, video is set to XDCAMHD 50 PAL (upper field first) and set starting timecode is off. 

When I use a different codec (also within the MXF OP1a wrapper) like AVC Intra the original timecode is preserved. When I chech the timecode overlay in the 'effects' section the correct timecode is shown. But when importing the file back into AE it always starts at 0:00:00:00...