Not Showing Group by on Some Custom Fields in "Team Worklog Reports Lite"

Question

I am using "Team Worklog Reports Lite" that provide to Group By Result on Selected Field,

Its Allowing Group By on Custom Fields (Created by Me) but not showing all Fields ... Some Custom Fields are missing ...

amar jeet singh sindal · Answer

Developer, who is working on the ticket is mentioned in Developed by Field.

Nic Brough -Adaptavist- · Answer

But what types of field are each of those?  And what type of field is developed by?

amar jeet singh sindal · Answer

Thanks @Nic Brough -Adaptavist- ,

I have a Custom Filed "Developed By", that is not showing in Field Selection List .

but another custom Filed "Review By" is showing ...

Please refer below Image.