Library parts are filtered based on the object tool - even though all object-related tools bring up that same dialog.
If you saved your object as a window, it will not show up with the object tool, only the window tool, for example. Doors only show up with the door tool. Etc.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB