1 monitor black when lid closed, other on, laptop screen remains on

[Mike Lynch 0]

First of all...please don't recommend I change my power settings or what happens when I close the lid option - those have already been set (see attached pic) and this configuration (described below) has been in use for the past 2 years with no problems. This just started happening - and not after any system update, either.

CONFIGURATION:
Dell Precision 7540 connected to docking station WD19DC via the double USB-C cables.
External monitors are Philips 276Es connected to the docking station via HDMI cables.

In the past, when I powered on my laptop with the lid open, all 3 monitors would power up and my desktop would span all 3.
Laptop display is #1 and externals are #2 & #3 with #2 being set as the "main display"
When I close the laptop the 2 external monitors go black for a few seconds and then come back up and my desktop spans perfectly left to right.
But a few days ago this started happening...
When I close the laptop the 2 external monitors go black for a few seconds and then the left (#2/"main") comes back up but the right (#3) says, "No Video Input".
And the real oddity....if I right click my desktop and select "Display Settings" 2 monitors are shown, but one of them is the laptop screen and not the 2nd external monitor!

What am I missing? Thanks in advance.