LabVIEW Timing Issues or Abnormal Behavior With Cortex XDR 9.1

Issue Details

I am running multiple applications developed in LabVIEW, and after installing Cortex XDR version 9.1, I observe abnormal behavior in some of my systems.
The issue does not affect all applications, but a subset of 10-15 VIs, typically larger applications.

Observed symptoms include:

• Incorrect timing behavior in applications
• Unexpected changes in signal outputs
• Issues involving Timed Loops
• No crashes or blue screens, but incorrect execution behavior

The issue appears only with Cortex XDR 9.1
Downgrading to Cortex XDR 8.7 or 8.9 resolves the problem
Replacing Timed Loops with While Loops may temporarily resolve the issue
Disabling the antivirus does not fully eliminate the behavior in some cases

Solution

• Downgrade Cortex XDR from version 9.1 to an earlier version such as 8.7 or 8.9, as this has been verified to restore correct LabVIEW behavior.
• Modify the application by replacing Timed Loops with standard While Loops in affected sections if downgrading is not immediately possible, to reduce timing-related issues.
• Monitor updates from the Cortex XDR vendor and plan to upgrade to a newer version such as 9.2 once it becomes available and validated, as it is expected to address the compatibility problem.

Additional Information

This behavior is caused by an incompatibility between Cortex XDR 9.1 and timing-sensitive execution mechanisms in LabVIEW. The antivirus appears to interfere with deterministic scheduling and execution timing, particularly in applications that rely on Timed Loops or hardware-level interactions such as motion control. This results in altered execution timing, including incorrect output signal frequencies and increased system rejection rates. Larger and more complex applications are more likely to be affected due to their reliance on precise timing and resource scheduling.