My Lc wouldn't start on the sidestand, my TDR is reluctant to as well.
Yammy twins are a bit fussy when cold and when the bike is on the stand the fuel in the floats is messed up because of the angles. With no vac to draw the tap open and feed more she wont start.
Easy fix, start it properly. Starting them on the stand means your already falling over if it goes wrong and its too late to stop.
Don't ask how I know