Car is a late 2018 model with just 33k miles. Linkage from gear lever to gearbox suddenly failed whilst in traffic about 150 miles from home - stuck in gear and impossible to select any other gear or engage neutral (gear lever flopping around and useless). Used Green Flag recovery to pick up the car and, when the driver/mechanic turned up at the roadside, he said he'd recovered two or three other Mazdas with exactly the same issue over the previous couple of weeks. Car was then taken the following morning to one of the repair shops that Green Flag use in the (Manchester UK) area. Parts were ordered (apparently a set of cables that are somehow bound together but need to be fitted as a set, rather than just replacing the one that's snapped) and repair was carried out. Parts approx. £220 and required 2hrs labour so final bill with VAT not much short of £500. Mechanics at the repair shop said that they had done at least two identical jobs in the previous week. So, what's going on and how big of an issue is this?

 

I did a quick search and find no recalls or TSB for this.
I also find very little information (zero actually) about this happening to anyone on any other Mazda forum.
I would conclude this not a significant issue at all, except for the few, like yourself, who may experience it.
I would look more to what in your area might be causing it.
Specifically, why Green Flag says they have done at least 3 repairs for the same issue in two weeks.
We once had a local shop that was replacing snapped emergency brake cables on Toyota Celica's.
I always request to see the used/bad part before paying my bill and my investigation showed the cable was cut (during an oil change).
Caused by improper placement of the lift arms to the frame.
The new technician at the time was not properly trained on the Celica and inadvertently placed the lift arm where it would contact the cable.
It would either cut it directly or do so over several lift sequences during other service (oil change, tire rotation, etc.)
Obviously, I didn't have to pay for the repair and that ended the local Celica cable issue.
Not saying that is your issue but you never know until you investigate all possibilities.

 

On my last CX5 I suffered this in year 4 of ownership; low mileage.
Fortunately I took out extended warranty. Dealer said it happens occasionally;
never happened on any other vehicle
I've owned over 50 years of motoring.