I have a U4320Q with DDM setup and several different sources hooked up to the monitor.

I had DDM shortcuts setup in various ways =

Single input DP1

Single input DP2

DP1 + PBP HDMI1 etc etc.

So I usually switch over to a multi input view  and then hit the "Single Input DP1" to go back to my main PC as the sole display.

All of the shortcuts work great however about a few weeks ago the DP1 shortcut stopped working.

Clicking it does run it but nothing happens and I have to manually set the input source if I need to go back or bring up DDM and click through and change from there.

Suddenly Broken

"C:\Program Files (x86)\Dell\Dell Display Manager\ddm.exe" /SetActiveInput DP1

Working

"C:\Program Files (x86)\Dell\Dell Display Manager\ddm.exe" /SetActiveInput DP2

"C:\Program Files (x86)\Dell\Dell Display Manager\ddm.exe" /SetSubInput HDM1 /SetPxP PIP-Large

"C:\Program Files (x86)\Dell\Dell Display Manager\ddm.exe" /SetSubInput HDM1,HDMI2/SetPxP PBP-3b

I have tried recreating the shortcuts fresh in case they were corrupt, no change.

Tried running the particular shortcut from several sources in case the particular DDM installation on the particular PC had an issue, no change.

Drivers updated as per below in case it was the integrated Intel causing the issue like I saw in other posts, no change.

Running

DDM 1.51.0.2021

Win 10 20H2

Latest Discrete GPU drivers

Latest Intel Integrated GPU drivers

Any insight greatly appreciated, thank you