PCell CDF parameters are not preserved

Hi Team,

Issue:
I created a PCell and loaded the CDF parameters.
Whenever I change the parameters, it stores and updates the PCell accordingly. Even after re-opening the virtuoso, the PCell parameters are preserved.
Even if I do multiple parameter value modifications, the values are preserved. But at some point (not sure at what scenario it happens), the cdf parameters are set to their default values (i.e., nil in my case).
I am unable to find a way to debug, as the issue is happening sporadically. 

Observations:
i) I am having multiple instance of the PCell in various cells. Not every PCell parameters are reset at the same time, but eventually all the cells are getting reset after some time.
ii) Even the parameters are reset, then physical layout whichever modified remains same. Also, I checked the parameter value by querying in CIW, I can find the set value. This means only in the PCell query form, the visible parameter values got reset.
iii) The CDF loaded is base and not effective/user.
iv) I am not resetting the CDF with the callbacks at any place. Let say if I have done that, I can say the callback (if triggered) made the value to reset but at the same time, it should have changed the physical layout and the backend parameter values (querying from the CIW). None of the things happened. 

Apart from the above mentioned things, the parameters whichever is getting reset has the "storeDefault" value set to No. I am not aware of what this option actually does but from the name, I am suspecting it could be the reason.
Please let me know what could have gone wrong.
Also, please let me know what does the "storeDefault" option does as I could not get exactly what it is.

Thanks,
Naveen