MacBook Pro (Touchbar) not properly recognizing external monitor anymore

Hi all!

So, I've had my Dell U3417W working properly via DisplayPort at 60Hz previously as a secondary display on my MacBook Pro.

Two days ago I added an old display with DVI via a DisplayLink USB32DVIPRO USB-DVI adapter, and both screens were working fine (massive real-estate; it was a joy).

Today I turn everything on again, and the DVI display works, but the DisplayPort one does not. The Mac recognizes it, switches it on in the proper multiscreen configuration (I see my desktop at the right resolution), but after a split second it disables it again, and keeps looping in this behaviour until I unplug the display again.

I've tried:

- disconnecting the USB-DVI screen

- uninstalling the DisplayLink driver

- resetting NVRAM

- resetting SMC

- updating MacOS with todays update (the one for the weird-character-crash)

- reinstalling and re-uninstalling the DisplayLink driver

If I re-install the DisplayLink driver the smaller screen works just fine.

The large Displayport screen works fine with another computer (PC), also over Displayport.

What else could be causing the display to be seen as being disconnected right after it 'comes up', and what can I try to reset (hoping it's some prefs files) to get this working again?

Help me Obi Wan Kommunity, you're my only hope!