If you just resize the window BEFORE you take the screenshot, then it will be OK. You should not to expand the window to stretch over the entire desktop. But I give up trying to explain it.
Anyway...
Since both ethernet and DP connections are defined automatically by integration, then it is not a manual error in the setup of the connections.
What I can think of:
Is the ethernet port on the MP377 w/o WinAC MP setup as in the project ?
There is no IP conflict anywhere ?
Disconnect the MP377 w/o WinAC MP, then try to start the WinCC Flex RT from your PC (important: same PC as you use to program the WinAC MP controller), does the RT then connect OK ?