Issue with a monitor exiting from sleep mode, want a sanity check before proceeding with getting a new monitor.

So I've got an old dell ultrawide, probably something like nearly a decade old (Just checking my drivers now shows the most recent ones are from 2007, lol). I've been using it as a secondary monitor for a while now, but recently I've been having issues with it coming back on after my computer has gone to sleep.

While the computer is powered on, the monitor remains black, but the computer acts like there is still a second functioning monitor; I can drag applications over to the dark monitor, etc.

If I turn the monitor off and on again on again using it's power button, the display briefly shows the desktop, and then the screen goes black again. For a while, disconnecting the DVI-HDMI cable I use and reconnecting it would turn the display on, and it would stay on, but now even that only lets me see the desktop for a second before the black screen returns.

I'm running Windows 10 with a Vega 64 card, and I've updated all the radeon drivers. To me, this seems like an issue with the monitor, since I haven't had any issues with my main display. I just want to get a sanity check before I start shopping for a new monitor.

[edit] I have tried other outputs on my card as well.