[GRASS-user] v.buffer doesn't create single polygon

I am attempting to buffer a line using;

v.buffer input=lmr output=lmrb type=line buffer=1500

Rather than getting one polygon, in several sections along the line I am getting many individual circles.
I have ensured that the line has only one category using v.category and outputting to a new layer.

According to v.clean input=lmr output=lmr5 type=line tool=rmdupl there are duplicate arcs.

I am a little stumped and would appreciate help.
thanks in advance.

Craig