When using S3D I get this issue where the extruder skips extruding on a level bedplate. I have some samples below. I've been looking at your FAQs and none of them cover this.
Is that the first layer? There is a section on their print quality guide for problems extruding on the first layer, so I would start with those suggestions.
It may be a filament issue, or your extruder has a problem. If the diameter of the filament varies significantly, it can either jam the extruder because it's too fat, or produce thin spots where it is too thin. I have a MakerGear M2E, and there is a tension adjust on the extruder drive system. Mine was initially too loose, and occasionally it would slip, producing holes in my prints. I've also heard of problems with "lumps" in some filament that don't melt uniformly, or can clog a fine nozzle.
Also, if you try to print too fast, the extruder may not be able to melt the filament fast enough for the drive system to be able to push the filament through. Given that the problem is intermittent, you may be operate "on the edge", and some minor variation in the filament is pushing it over the limit.
Could be some debris in the extruder wheel which causes a intermittent slip.
Could be (I alredy experienced that myself) that depending on your extruder design
that the grub screw which holds the extruder wheel is exactly in line with the filament.
Then you could see exactly this effect every turn of the wheel....