I've had this same issue with my 2012 Mazda 3 (skyactiv) for more than a year. Eventually gave up and took it to the dealership while it was failing. The less than capable mechanic tore into the system, claimed the switches and clock spring were all defective. They kept my car for a week while ordering parts. Then they also replaced the brake switch. The issue continued. A month later I caught it acting up while I was on my way into the dealership to get other service. This time they concluded it was my battery was going bad. Replaced the battery. Haven't had a problem since. Evidently if the battery charging isn't within specs, items like the cruise control will get disabled until the next time the car is turned off/on and the charging diagnosis self check is redone. So, if I had only changed my battery out a little sooner, I could have spent about $100 and an hour to replace the battery. Instead I have spent close to $1000 at the dealership plus over a day of my life by the time the "Experts" figured out the real reason. (At least that $1000 included replacing the battery). I'm posting this hoping to save others the pain of such apparently unrelated issues having a cause and effect.
ahh the pains of owning a modern automobile, yes this has been concluded here and on other forums to be the root cause of the cruise not working. Our car is not even the worst with all this self check and everything tied to everything else crap, try owning a Mercedes or a bmw, or anything 2015 and newer, the can bus controls everything and now so much is tied into this that 1 issue seemingly unrelated can cause a waterfall of other seemingly unrelated issues. hell our stock radios are tied into the can bus why does our radio need to be tied to the can bus, well that nifty little screen that gets half blocked by the steering wheel (where I sit in my car) displays all the warnings and processes everything (the computer does this just saying) it also is tied into the radio for song info, well since this screen is tied to the can bus so is our radio since they have to work together, but they should have done this differently.
tying a basic radio like the 10-13s have to the can bus is useless as it does not do anything but complicate everything. yes that's how you get the maintenance reminder and the mpg read outs and what not but the radio does not have to be directly tied to this for all these nifty features to work, it must simply interface with the screen, so you can get song data, but that's why you must spend $100 just to change a radio in this car because the PAC harness connects and talks to the can bus and retains all the features, which having a radio that simply talks to this and is not directly tied would be simpler for the end user. the more modern the car the more modern the problems its going to have. the more tech the more tech problems.
car makers have also been trying very diligently to prevent changing the stock radios recently look at any new mazda the factory radio is a tablet glued to the dash, an aftermarket radio requires a special kit that relocates it and makes the interior look like a kids coloring book because you get a dead tablet on the dash and a radio stuffed somewhere it was not meant to be. plus they are integrating all these features cars have now into the radio menus and buttons this also inhibits changing from the stock radio. its kind of foolish to me from an end user stand point to do it this way (I know why the car companies do it because it keeps you buying their stuff after you buy your car) but from an end user perspective it is foolish because im going to find a way to change my radio/speakers etc and there will be an aftermarket catering to this no matter what you just need r&d time and money and a market for it (which is there for aftermarket car stereos) and kenwood, jvc, metra, pioneer, sony etc are all large companies like the car companies and can spend r&d effort on modding a car to get their stuff to work in it.