So it's joining the the 2 sections to go over 255.
I would say that's a bug they need to look into as it's not stitching it correctly.
I highlighted and selected all tracks and regenerate that section and it still generate 2 files per tack.
It should be fixable.

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RB-241-Join.png (420.15 KB, 168 downloads)
RB-241-Join2.png (415.38 KB, 169 downloads)
RB-241-Join3.png (399.54 KB, 169 downloads)