Hello Imm,

By reading the little information you have provided I do not see a reason that could result in the denial of the Non Lucrative residence permit, unless you had failed to provide with the remaining documentation related to the proof of dwelling and evidence of regular income.
The possible explanation for the delay in the resolution may be that there is an overload of work at all immigration offices, and the applications can even take up to a year to be resolved. However, you can file a formal petitition of information at the corresponding oficina de extranjeros and find out what is the current status.

Best Regards,