Why the budget is not changing on adset level?

 

Once you open the campaign in edit mode, the budget that you're seeing is the budget for that master adset. This means that if you have for example 5 adsets from that master adset, you'll update the budget on all of them.
If you select a specific adset on the manage page, then it does not count as an update to the master adset, just an update to that specific adset. Hunch does an update for that adset on Facebook, saves the new value for that specific adset in Hunch system, and does not touch the budget again unless you specifically change the master adset or the budget for that specific adset again. You shouldn’t ever make any changes to Hunch ads through FB, as for the budget, it can be changed through FB, but it’s always best to edit Hunch campaigns via Hunch.