P2724DEB, loses USB-C when switching Inputs

DellP2724DEB - Lost USBC when switching Inputs

Recently had this delivered by my work as a new teams monitor. 

My setup is as follows : 

Surface Pro Laptop connected by USBC to Dell Monitor

Dell Monitor Daisy chained through Display port to MSI Monitor 

Keyboard and mouse connected through usb hub to USB-B socket on Dell Monitor

Personal tower PC connected through Displayport to Dell Monitor

Personal Tower PC connected through HDMI to MSI Monitor

Both work individually...

I can connect laptop to USB-C, power up and shut lid - both Dell and MSI monitors have correct displays, keyboard mouse works, and onboard camera works for Teams (Dell monitor set to USB-C Input)

Personal PC works - both Dell and MSI monitors have correct displays, keyboard mouse work (Dell monitor set to DP Input)

HOWEVER - If I switch from (working) USB-C connected Laptop to Displayport (to use personal PC), and back again - the monitor just says "No USB connection found" or similar and refuses to acknowledge the laptop - unplugging the USBC and pluggin back in makes no difference. 

Only a reboot of the laptop (and not using the switch input function) restore proper working...

Any ideas as this is a bit of a deal breaker for me as often have to switch to personal PC for research...