Hello,
 
Before to answer of the direct problems I need to do some notes.
 
1. We recommend to use the jqGrid version where the problem persist. You tell us for version 5.2.1, but you use 4.6, which we think can come to some uncomfortable situations.
 
2. It is always good idea to set id row – this can be done either in the description of the colModel (key : true) or with the appropriate reader in this case localReader. When you set this you will be sure that there will be not a problems getting certain row and some other important commands. It is not good idea to let the grid create the ids.
 
Now to the problem : to do what you want you should use the getLocalRow, which return the data as it comes to the grid – i.e the original data.
 
In your case there was a bug when scroll is on and no id is set from the developer (i.e. the grid creates internally the id). The problem is fixed in GitHub and you can test it.
 
If you have difficulties to get the last build from GitHub, please let us know.
 
Kind Regards