Generally, the hit boxes for inanimate objects seem to be too small (or oddly positioned). By inanimate objects, I’m referring to various barriers, barricades, doors, supplies, mining drills, siege weapons, and so on that you are supposed to destroy in PVE events or at heart objectives. To clarify, I never have any trouble hitting these with ranged abilities, but I have lots of trouble hitting them with melee abilities. Some objects are more difficult than others.
Last night I was exploring Diessa Plateau and had this difficulty repeatedly on my charr guardian with melee weapons across the whole zone. I’ve had similar problems in other zones and with other professions, but this zone & profession combo make the problem highly visible. There is an event at Bloodcliff Quarry where the bug is easily tested, where you are supposed to destroy mining drills. I was standing on the drills and running around them to try to find a point where I could hit them. There was only one narrow, unintuitive spot by the drill where I could stand and still deal damage to it. Doors and walls pose a similar problem – the hit box appears to be located too deep within the door, or too high up, so that they are very difficult (impossible?) to melee from certain sides and you have to swap to a ranged weapon in order to break them.
Please tweak the hit boxes on these to more closely match the actual object. It seems a bit silly to run around looking for one sweet spot to melee a huge inanimate object.