ok, so i went in to file>libraries and objects>open object and checked the "placable" option, now it's accessible in the objects pallet. there isn't an option to save as placable when creating it. just for fun, i tried to do it as "new object" but that's not intuitive, i'll have to read up on that. i tried it, and didn't see a way to save my new object. not intuitive.
Saving as new object is exactly the same process as saving as a custom component.
The difference is it will make the object 'placeable' and put it in your embedded library.
Saving as a custom component will also save to the embedded library, but as you noticed, the object is not placeable by default, as it is designed to be access from within another object.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10