Hi,
Thank you for posting your query to us.
I am afraid that I was not able to reproduce the issue. Please refer to the following steps that I tried to reproduce it.
1. Created a sample that has additional column in gridgrouping control with checkbox.
2. Run the sample
3. Change the status of checkbox in selected record
4. Status will be changed
Also I have created a simple sample to test this issue and it is available in the following link.
http://websamples.syncfusion.com/samples/Grouping.Web/5.1.1.0/66962_1/main.htmPlease have a look at the above sample and if still the issue exists, could you please try reproducing it in the above sample or send us the reproducing steps so that we could sort out the cause of the issue and provide you a solution?
Thanks,
Melba