Found on 220.127.116.111
When using guides on artboards that are not positioned with the top left at (0,0) seem to display wrong positions in the guides manager.
Horizontal guides on artboads that have their Y position not at 0.
Vertical guides on artboards that have their X position not at 0.
When adding a new guide it is still correctly inserted in the center of the artboard, but the displayed position in pixels and percentages is wrong and mostly negative. The size of the artboard seems to also affect the value.
As the guides are still placed at the center correctly, it looks like it's only the calculation for position relative to the selected artboard displayed in the guides manager and not the internal global position of the guide itself.
I uploaded a video of the behavior as well.