Are all the lenses compatible with 7d? Especially EF-S? Anyone having a autofocus issue with 55-250mm IS lens?
Short Answer: Yes.
All EF and EF-S lenes are compatible with your 7D. You should not have any autofocus problems if camera and lens work well. Otherwise you should check the lens on an other eos (if you can) respectively the camera with other lenses.