I had 3 external monitor setup connected to my Mid 2015, 15" MacBook Pro. This used to work fine with OS X El Capitan which I have been using for past 3 years.
I recently upgraded to macOS Mojave, and now my MacBook will only connect to any of the 2 monitors at a time. I will not connect 3, and can have HDMI and DVI, or DVI and VGA, or VGA and HDMI, but won't connect all the 3 at same time.
For my workflow, I need 3 monitors to be connected. Any reason which may be preventing this setup from working in macOS Mojave? I should add that the machine won't detect the 3rd monitor, but if I unplug either of them, is does see the 3rd one.