Help with Arducopter spline turns

Hi all. Having a bit of a weird issue I haven’t come across before.
After updating my Arducopter to the latest version, my spline way points seem to not be working properly.
The flight I experienced the issue on was not a typical mission. 12m line spacing is the main mission parameter that is out of the usual for my missions. Not sure if this can be the cause of the issue?
Please see video to understand the issue. There is definitely something visible in Mission Planner but only at max zoom level. See other video for that.
What could be causing this? Am I missing some basic but critical parameter that could be the cause?
Any advice/tips/tricks will be very appreciated.

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