Moving objects between different artboards is bugged.
If something falls partially outside the bounds of the artboard, it will remain on that artboard in the layers panel, until you try to resize or move it, upon which those objects will disappear, and go to other artboards.
This action isn't recognized by the Undo action, making it impossible to correct mistakes and forcing me to do more work re-aligning everything. This is kind of antithetical to the entire purpose of artboards, and it's not how objects/artboards behave in similar Adobe environments.
To reproduce:
-Move a group containing multiple objects from a large artboard to a smaller one
-Objects are correctly listed in the smaller artboard in the Layers window
-Move or resize the group, and any objects touching the edges of the artboard will disappear from the group
-Using Ctrl/Cmd+Z will not Undo this