Probably everything they do is designed exclusively just to p!ss you off. Not that it's all that hard to do. There's no good reason why different locations really, none that I can see anyway. Maybe they just want to keep the punters on their toes. They don't widely release the various methods of attaining preboot, they were found at our level by trial and error after they changed it in a new model. Have a look at the initial post here, the first nuvi series 3xx/6xx you just held the power key down. A couple of series releases later, nuvi 7 series can be an absolute mongrel to find preboot. Zumo 660 has it in the LOWER left corner. Drive devices need to be pressed just above and between the G and the A, reportedly.

Oh on a different topic, 2018.20 NA map is behaving oddly on my 255w, I thought it was the latest FW but I confirmed OSM map worked flawlessly. In simulation mode, Garmin map would gets "stuck" pretty much every single time.
Two possibilities, the device or the map. Hard reset it and if it still does it replace the map image.