Today while starting measurements, all of a sudden the plotting function stopped working and we were not able to plot anything. At one point I wanted to set all values on front panel as defaullt so I used the option from labview in edit, and I ran the VI. By mistake I set the value of rotator to 560. The VI crashed. Since then the plotting stopped.

The issue was that when we use set all to default, labview also sets non user controlled stuff to default, like loop configurations. The plotting loop had some time contsant and labview overwrote it.  I tried to make the function again with period 100. Now, the loop works fine. This was the only issue for now, but maybe we will have similar issues in future, coz idk what other values might have changed (for other vi). 

I have saved pdf of front end backend as MapBirefringenceVI (in labview scripts), so that we can use for reference in case something weird happens.