As per the title, the grid in the manual cache is not consistent in its position. If you move the view, the grid alignment changes, meaning it is impossible to even know what area you are supposedly (but not actually) caching. This applies to both selected and non selected areas.
Regarding the function of the manual cache, since the day the game was launched, manual cache has not worked. Selecting any area at any detail downloads the requested data and then immediately discards any non photogrammetry scenery. This can be observed with the stupidly small file sizes (just a few KB) of manually cached non photogrammetry scenery despite the large amount of data being downloaded as can be seen in the data usage tracker.