No version ever allowed you to do concentric infill for the INSIDE of the part. Version 2.2 and Version 3.0 BOTH allow you to do concentric infill for the outer solid layers. So no functionality was lost at all between the two versions.
If you want concentric infill for the INTERIOR of your part, you are welcome to request that as a new feature, although, I have no idea why you would want that. The other internal infill options would work much better.
did you try to set the infill to 100%? For me printing Ninjaflex with concentric infill works like a charm and the whole part gets a solid concentric infill.
If this is not what you need, could you explain or do you have pictures on how you used the concentric infill in the old version?
Simplify3D v3.0 on Creatr HS