Normally by default Isight could output the peak stress value from the Abaqus odb file. Since Abaqus adopted the direct solver, for some simulation jobs Abaqus may show the job completed successfully in the status file (.sta) but certain (if not all) field variables are not available in last few frames as indicated by a Window showing following information; 

"The selected Primary Variable is not available in the current frame for any elements in the current display group." 

Therefore, Isight will automatically output the stress (or other variable) value from the last available frame, not necessary the data from actual last frame. Users must open the odb file to check if the field output is available at the last frame.

To resolve this problem, users can parse the odb file with a python script (Check here https://swym.3ds.com/#post:20082 for more information). To check the actual last frame number (numFrames), use this 

    odb = openOdb(odbName, readOnly=True)

    numFrames = len(odb.steps['Step-1'].frames)-1

In order to find the actual last frame number, the frequency of field output should be every frame (n=1). The last frame (maxFrame) which the data is available could be found by: 

for step in odb.steps.values(): 

    for frame in step.frames:

        allFields = frame.fieldOutputs

        if (allFields.has_key(Stress)):

            maxFrame = frame.incrementNumber

Then, by comparing  the two frame numbers (numFrames = maxFrame? ) , users can verify if the value from Isight is the data from actual last frame of Abaqus simulation.