Just looking at the excel sheet, who ever picked up the files which went into "IP" between 10th September and 18th September is holding them all up, wonder if the case processing worker has gone on disability?
Most probably it is the same case processing worker who has picked up all of the March 1st week files, which are still in the status of "Application Received".
You can be lazy and be a bit behind, but this is taking it to all new level. Look at the excel sheet, March applications look like they are just sitting there in the middle to make Feb and April applicants look more prettier with different colors all around them.