When I try to run external mode, simulink stuck, no input and output.

I was doing real time experiment and almost near to finish it.I am using real time mode since December 2023 and it was working fine. Today in the morning when i am trying to run the same file, when I click on run simulink stuck and then I need to close it using task manager. I don't know what can be problem. I used simple block but it's still not working.

There is no change in T, the below screenshot shows the condition, when I open scope it has dialoug "Frozen".

I am using NI PCI.