I had a similar occurance two days ago while riding home from work.
One difference is that I could shift down normally.
I`ve been riding to work every day for the past 4 weeks without any mechanical problems. The scoot warms for a couple of minutes while I tie a dufflebag to the back seat and finish gearing up. I have to run a 1/4 mile of gravel driveway from work, then 4 miles of pavement into town. I booted her up to 60 mph in 5th gear and she runs like a champ for about a mile, then loses power and dies. Look at fuel gauge and it is down between 1/4 full and the red empty mark, so I switch to "REServe". I pull over to the side and try to start again a time or two. No go. Open tank cap and rocked bike. Still enough gas to slosh around. Sat there thinking for a minute or two trying to figure out what is going on.
Try starter again, and we are good to go.
Switched back to RUN because I was not convinced fuel level was down to where REServe is needed. I was right, it ran for 5-6 miles to service station where I filled up with 10.5 liters. Still had ~3 liters in tank.
Has been starting and running fine since then.
Also checked operation of reserve pickup tube previously for 2 days running with a full tank, to be sure it wouldn`t give me contaminated fuel from bottom of tank when I really have an almost MT tank.
Still have no clue what caused loss of power or why it started again after 2 or 3 minutes sitting with the engiine off.