U2724DE - problems with Thunderbolt 4 connections

New computer set up.  Dell Ultrasharp 27 U2724DE.  PC is an MSI CubiNUC.  Intention was to connect keyboard, mouse, network cable and run power via the Thunderbolt cable to the cube.  Seemed to work initially but then just would not work.  Monitor kept on reporting it could not find the thunderbolt cable.  Sometimes it did, sometimes it didn't.  Currently running with the mouse, keyboard, network cable, power via the cube and an HDMI cable which is a waste of ports and potential of the monitor.

Have updated the drivers.  Struggling as whilst I'm ex IT staff this is me jumping from a 12 old system to this one and I'm at a loss whether its a faulty cable, or port or even damage to monitor during shipping.  Help would be appreciated.