I am using Version 5.1.2, and the issue is not fixed. I think it would be good if S3D added the infill % setting back in for the raft.
I use a FlashForge Creator Pro and print ABS using ABS juice for adhesion on a glass bed. S3D-Version 4 made functional rafts out of the box. I was unable to get Version 5 to make a raft that was well made and not dragged from the bed by the extruder. I think the raft problem was mostly unstable base layers and incomplete top-layer infill. Email exchanges with S3D did not help. I finally tried using Multiple Processes based on Z height to start the print using a higher Extrusion Multiplier. I finally achieved a good raft, and the finish on the bottom of the print was satisfactory.
I use a layer height of 0.2mm, so I used the Multiple Process Wizard to make a change in process at the height of the top of the first layer of the model (0.2mm). Process 1 is used by S3D to print the raft and the first layer of the model. For this process, I set the Extrusion Multiplier to 1.30 with automatic extrusion width. For the raft, I used 1 Base Layer (to reduce height as a moment arm during infill) and 3 Top Layers. I used a separation distance of 0.4mm (up from 0.14 prior) and an above raft speed of 50%. I turned the extruder-mounted fan on 60% at layer 4 to cure the top layer of the raft and reduce adhesion between it and the print. I turned the fan off at layer 6, but I presume this is ignored because layer 6 is the start of process 2.
For process 2, I used the same layer height, an Extrusion Multiplier of 1.00, and turned the fan off at layer 6. Process 2 is the primary process for the rest of the print, so the settings in it are paramount for everything except the raft (and the first layer of the print). I had to be sure I was getting the settings right for each extruder for each process. It was easy to overlook that.
I have attached sample S3D files for inspection, if that helps. This print had a perfect raft and easy separation.