Issue with UR3 CB3 Robot - Teach Pendant Freezing during Program Execution

We’ve been successfully running programs on our UR3 CB3 robot using external control and RTDE interface. However, we’re now facing an issue where the teach pendant freezes on the “waiting program” screen when initiating program execution. The PC segment receives data from the robot without any problems.

This issue suddenly occurred without prior issues. Anyone can please advise on troubleshooting steps and resolution?