I encountered a rather odd problem when using Inkscape, a vector graphics program. I was unable to create unions joining two paths because each was in a group with only one a member. I could think of nothing that I'd done that should have created any group, and a group with only one member is an odd thing in any case. I only discovered the grouping because I had eliminated the other possible reasons that the paths should not form a union.
Each of the two paths was originally a text object, entered separately from the other. Perhaps in recent versions of Inkscape text is always in a group, even with just one character.