Hi.
Yup, found a solution.
My Suzuki is 2012 KQ 750 axi. So with help from a friend who knows these machines better than his own five fingers, we had a chat and told me to change gear lever position sensor.
So, went to this site https://www.partzilla.com/catalog/suzuki/atv/2012/kingquad-lt-a750xpzl2/gear-shifting and picked the right year and engine and under gear shifting ordered new OEM part number 29 and that fixed the problem.
Also, had the same problem that when in L gear it did not show in the gauge cluster.
One thing what i noticed is that the problem occured only after when engine had reached it`s working temperature and fan had kicked on for atleast once. Before that, everything worked fine.
Now it has been over a year after changing the position sensor and everything works like a charm!
Sensor is located on the right side of engine, between exhaust and engine, outside.
Attached picture below, red circle shows the location.
For changing, loosen or take off exhaust, otherwise you have very minimal and tight space. It is dooable without looseing the exhaust, but belive me its very challenging.
All the best and let me know if it worked for you!
Thortobe's post in 2012 Suzuki King Quad 750 sputtering in L gear was marked as the answer