Sorry for the delay in answering. This issue is resolved in Notion 6, where you can place chords anywhere in a measure, without needing to attach it to something as well as drag chords anywhere.
But for Notion 5, there is a workaround where you add rests in the measure first, attach the chords to the rests, then hide the rests. (There's a more sophisticated version of this workaround where the rests are entered in voice 2 and then hidden - this allows other rhythms to be added in voice 1 that might not line up with the chords)
-Chris