The "truce of the watering hole" -- is it completely discredited?
Cleaning stations offer a pretty strong individual incentive not to attack, those that attack do not get cleaned and thus get riddled with parasites. Watering holes are just the opposite there is no advantage to not attacking and in fact a decent advantage for attacking, (a meal) many predators hang around watering holes just because the draw prey. 

To put it another way the genes from lion A say hunt things at the watering hole, the genes from lion B say don't, Lion A is going to have more meals and thus more offspring than lion B therefore the genes to hunt at the waterhole will spread. Lion B gains no benefit from not hunting at watering holes that can offset the very large and immediate advantage lion A gets. This is a good general test to why group selection generally doesn't work, even if all lions were type B as soon as lion A occurs from a mutation it has a huge advantage and drives out lion B's genes. 

There is quite a lot of evidence that predators often concentrate around watering holes, heck this is how crocodiles make a living. The idea that lions do not is an out dated and stems from early observations done only during the day (when lions are mostly inactive yet close to watering holes to hunt at night), spread by fiction writers and reinforced by advertising and poorly researched articles. 

https://www.nrcresearchpress.com/doi/abs/10.1139/z77-235#.XkxeG2hKhPZ

https://academic.oup.com/beheco/article/23/5/970/232520

The Serengeti Lion: A Study of Predator-Prey Relations
By George B. Schaller

Seasonal Diet and Prey Preference of the African Lion in a Waterhole-Driven Semi-Arid Savanna