Canon lenses with an Ultrasonic Motor have natural slippage between the focus ring and the lens' focusing elements.

The technology for this type of AF motor was first developed by Canon, who refers to it as an UltraSonic Motor (USM). It has since been adopted by many lensmakers and is known by such monikers as Silent Wave Motor (SWM) - Nikon, Supersonic Wave Drive (SWD) - Olympus, Supersonic Drive Motor (SDM) - Pentax, Supersonic Motor (SSM) - Pentax, Hyper-Sonic Motor (HSM) - Sigma, and Ultrasonic Silent Drive (USD) - Tamron.

When you reach the end of the focus travel in either direction you can continue to turn the ring forever and it will just slip. If you turn the focus ring in the opposite direction it should move the lens no matter how slowly you turn it.

If the lens is at the minimum focus distance and you turn the focusing ring clockwise as viewed from behind the camera, the ring should slip. If you turn the ring counterclockwise any movement of the ring should move the lens until you reach the other end of the lens' focus travel just past infinity.

If you are turning the focusing ring very slowly in a direction that should move the lens and the lens is not moving, but a faster, more forceful movement does move the lens, your lens needs to be examined by an authorized Canon Service Center or other lens tech that knows what they are doing. It could be that the "slippage" just need to be adjusted. It could also be that the focusing helicoids and/or collars have been warped or mis-shapenned and need to be replaced. When this happens, though, it is usually only at one focus distance somewhere between MFD and infinity.

I've not heard of this being much of an issue with the EF 24-105mm f/4 L IS. The EF 50mm f/1.4, on the other hand, is very easily damaged if bumped from the side while the focus is near the MFD and the front of the lens is extended. When the problem first begins to occur, a quick, forceful movement of the focusing ring will usually move the lens. If the issue is a bent collar or helicoid, or worn out rollers on the guides that follow the grooves, the problem will usually get worse until eventually the lens will be stuck and neither manually moving the focusing ring nor trying to use AF will move it past the rough spot.

Based on the video that has been posted since the above was written, I'd be inclined to believe that the end of one of the slots in the focus helicoid has become misshapen on the short focus end. It's also possible a screw holding the nylon roller that moves up and down the slot has become loose.