Hi, I realise this is an old-ish post but answering as much for the benefit of others who find it while troubleshooting the same problem (like I did); This is a current problem with the work-in-progress Monogame 3.5 and it does not exist in the latest stable build, 3.4 (at least as far as I have experienced.)
Just install 3.4 as shown here How to install MonoGame 3.4 on Linux and use the “Linux” build target. DesktopGL will (afaik?) replace this in 3.5 but is not an option in 3.4.
You can check your version of Monogame by opening MonoGame Pipeline -> Help -> About