honesttt:
There can be multiple factors that can cause this but I would not worry necessarily, please see below;
- If your 3 years / 5 years time frame after becoming permanent resident is not quite up. If it is still one plus month away then USCIS may delay this to fulfill the eligibility requirement.
- Background checks can be second factor. You can always call FBI and they will confirm at least the status on your FP's. However, Name Checks are tricky and they don't disclose or elaborate any information on it. Please note FBI and USCIS have done collaborative efforts on this issue in general to conclude N-400 within 6 months with few exceptions.
- Take an InfoPass and go to Nashville ASC. Officers working on infopass are very helpful at Nashville office.
I hope this is helpful. You can find FBI Number on this forum if needed.