I have a 2014 iX35 and 2 years ago the rearview camera started to play up, especially when it snowed or heavy rain, but most of the time it functioned. Hyundai Wolverhampton's stance is that if it's working when you take it in to have it sorted, then they will not investigate the problem, even though you report that it stops working after heave rain or snow. The same goes for my radio that keeps losing it's signal. The day I took it in for sorting it worked perfectly, so it was returned without any investigation being done. My rearview camera stopped working all together and after reading that Hyundai would charge between £200 & £350 to sort it, but several people had bought new cameras on e-bay or Amazon, I decided to do the same. There are loads of cameras to choose from. I decided to purchase one off e-bay for £6.50p, which I fitted in the same location as the original camera. It even came with a hole cutter, as the fitting was a little larger than the original hole. There are Youtube videos showing you how to go about changing the camera, stage by stage which is basically removing 4 screws which allows you to remove the plastic cover, then 13 nuts, which allows the whole section that houses the rear number plate lights, the boot opening sensor and the rear view camera. Once removed you can fit the new camera. The connections are straight forward Red is 12v dc positive, Black is 12v dc negative and the yellow is the video feed wire. I soldered the connections, as the wires are quite small and connectors may well fail. Best to check that it works correctly, before replacing all the nuts, etc. Some cameras come in a square housing, and if the housing is not in the correct plane the view on the screen can be mirrored, or side on. As my camera was round I could just rotate it into the correct position.
The whole job took me about 3 hours but saved a lot of money.
Hope this helps.
My next job is to sort out the weak aerial signal to the radio, which I suspect is water getting into the roof pod, which contains the aerial and amplifier.