In your case state.laptops.earmarks is an array, and you are manipulating it by its array index state.laptops[index]. Vue is unable to react to mutations on state arrays (by index). The documentation provides 2 workarounds for this:
// 1. use purpose built vue method:
Vue.set(state.laptops, index, laptop)
// 2. splice the value in at an index:
state.laptops.splice(index, 1, laptop)
Although it is documented, I’m thinking a giant neon glowing sign on that page that says “You will waste hours of productivity if you don’t know this” would be a nice addition.
You can read more about this “caveat” here: https://v2.vuejs.org/v2/guide/list.html#Caveats