It sounds like yourr recorder is recording the _signal_ the way it is,
whatever the aspect ratio.
(There is no real difference in the signal, as such. It is only the
information in what aspect ratio it shall be displayed that is
different.)
The problem is caused by the limitation in the DVD-format, that only
supports one format (flag) per "title". That makes it difficult when
recording a broadcast signal that changes the flag on the fly.
Anyway, it works good for playback on the same (or similar recorder)
that can used the extra information of the aspect flag and change on
the fly.
For a one time playback on a standard DVD-player, I manually change
the aspect ratio on the TV. But for the automatic aspect function to
work I do what you do and use a PC to change the flag.