I've been browsing the forum trying to find a solution to my specific problem but can't find anything specific. My graphics card is the Radeon R9 380 Sapphire Nitro. I have three DVI displays, one of these is using an active adapter to displayport. This was my original setup, and it works perfectly fine. However, when I connect the fourth monitor with an HDMI cable, the second DVI display loses signal. Ubuntu however, still recognizes that the display is connected.
The only fix I found is to disconnect and reconnect the HDMI monitor from the graphics card, which for some reason makes the DVI display recognize the signal and turn on. Going into sleep mode also produces the same problem, the only way to fix it is to disconnect and reconnect the display.
I should note that I dual boot into Windows, and it has absolutely no problem recognizing all four displays. Attached is a screenshot of my xrandr taken when the monitor was currently not detecting a signal.
I'm also using the amdgpu pro drivers from the amd website.
If anyone has any ideas it would be greatly appreciated.