hmmm, that's strange. Probably a bug, so thanks for the discovery!
You can also try unlocking all layers on the scene, select 1 layer and press 'Cmd + A' (Mac) or 'Ctrl + A' (PC)
This is the shortcut key to select all layers on the scene.
With all of the layers selected on the scene, you can R-click on any canvas object and choose Copy from the menu. Then try R-click/Paste on the new project. If that doesn't work, try marquee selecting (click and drag a rectangle acroos all canvas elements) and using Ctrl + C (copy)/Ctrl + V (paste) into new project (be sure to L-click on Canvas of new project before pasting)
Please let me know if either of these helps!