This also works for my 5120X1440 resolution, but I would also like a solution that did not require gymnastics.I have a temporary fix.
You have to launch the game while the ingame resolution is previously set to any 4:3 or 16:10 resolution equal or less than 1920x1200 (borderless window).
The workaround works only for a single session. You have to switch back to 1920x1200 (borderless window) before exiting the game, to be able to trick it next launch.
- Switch ingame resolution to 1920x1200 borderless window (for example). Exit the game.
- Launch the game. In the title screen switch back to 5120x1440 (fullscreen or borderless).
- Play. The minimap will not disappear anymore.