At £35 it's the cheapest DIY option to rule it out.
As the catch goes onto its first position the cable, in the 2nd unit, pulls the tailgate onto the second position of the catch.
Of course it could be an electrical issue but that will be harder and more difficult (expensive) to diagnose.
The tailgate also has trap sensors which play up at times, also low voltage plays havoc with convenience functions.
If you have a local LR specialist speak to them first and see what they say, might have dealt with the issue before.
I have changed one before and if you have some general DIY tools they are easy to change. You will most likely find a video on YouTube.
Please let us know how you get on and hopefully the cheaper option fixes it.
Note: I do not know if that actually item in the link fits your car, you would need to check the year