I am in the same situation.
I went through Campbell Cohen law firm who advised me to obtain all my documents in advance of the E-APR submission.
To avoid any delays, I paid all fees and submitted my bio-metrics and police clearance reports without prompting from IRCC.
My E-APR was submitted on September 8 2018.
There was nothing missing from my application and I have not received any request for additional documents.
I meet all eligibility requirements, however during my EE application the lawyer hurriedly submitted my application. I might have gotten a few work dates incorrect and not listed a Job because i was still trying to obtain job letters at this time.
The dates were corrected to match my job letters and i included for the one job that was left out when i submitted the E-APR application,
My lawyer sent me a screen shot in December 2018 showing the following status:
Review of Eligibility - We are reviewing weather you meet eligibility requirements
Review of medical results - You passed the Medical
Review of additional documents - We do not need additional documents
Interview - You do not need an interview. We will send you a message if this changes.
Bio-metrics - We do not need your fingerprints. We will send you a message if this changes.
Background check - We are processing your background check. We will send you a message if we need more information
Final Decision - Your application is in progress. We will send you a message once the final decision has been made.
I am now over the six months and no word, I am not sure if my application was denied.
I plan on waiting until the end of the month and cancel the application i there is no update.