Larian uses the terrain to create Advantage/Disadvantage much more frequently in combat. While this can make things more tactical and interesting, it also can make it hard to figure out what's happening unless you pay attention. You can assume it's just bad rolls unless you are watching the tool tips.
Dialogue could solve this and would also make the characters come alive.
"Ack, can't see!" complains a human without darkvision who missed due to disadvantage. Repeating this line every time would get annoying, but periodically would be helpful. Especially with variant lines.
"Can't penetrate!" says a fighter who gets a "miss" on a giant ogre because the monster's hide deflected the attack. (Hint: you didn't "miss" the giant ogre. You don't have the worst aim ever.) This could also tip off the player to try a different tactic.
"Ha, ha! Had the high ground!" gloats a rogue with advantage due to height when the attack hits. Again, not repeated every time this happens, just periodically. Especially if this same condition hasn't happened recently.