External display always blank on 2018 MacBook Pro

I have a 2018 MacBook Pro running Mojave connected to a Dell WD15 dock, which in turn, is connected via a Mini DisplayPort to DVI connector to a Dell 2001FP monitor.

When it is in this configuration, the Dell monitor always shows a blank screen. The only exception is when I switch the display arrangement to "Mirror." Then, for a brief second, the Dell monitor shows the mirrored display and reverts back to the black screen.

I can also get the Mac to display on the Dell monitor if I connect it via the dock's VGA connector.

There is no issue with the dock, the monitor, nor the connectors that I am using: these work perfectly fine with Windows systems as well as older MacBooks with Thunderbolt DisplayPorts.

Can anyone help? I have already tried resetting the NVRAM and SMC to no avail.