Gap between infill and walls for one filament only
I have observed similar issues between walls, not necessarily between the infill and the walls.

It is most likely that the viscosity of this filament is way different (less fluid) than the other filaments you print. Not only mechanical issues (to be precise: inaccurate positioning e.g. caused by loose belts) could play a part in this, but also printing speed. A more viscous filament needs more pressure and time to get the filament through the nozzle. This is exactly what happened in my case, because of different wall speed line settings (inner and outer), the filament did not flow fast enough leading to under extrusion. In your case you probably also have a higher infill than wall speed, so lowering your infill speed may mitigate your problem. Also, most slicers have an option to define the overlap between the infill and the perimeters/walls, you could also increase that for this filament.