The problem is not hiding in combat, but Larian not understanding that their 'small' homebrew changes break any kind of balance in the game. Sight cones are not supported by D&D 5e, thus the whole perception and stealth system got broken by their introduction and made worse by having sneaking characters not being locked in turnbase and on top of that the whole shift in game balance by turning jump/shove/hide into bonus actions for every class.
Implementing the actual rules from D&D 5e would 'surprisingly' solve the problem. You can hide in combat, but not in plain sight. Perception is 360 and you actually roll for stealth not trusting on you noisy heavy armour to sneak up on someone who is just looking the other way.
