Part of our group got stunned before Initiative was rolled:
Stunned
- A stunned creature is incapacitated (see the condition), can’t move, and can speak only falteringly.
- The creature automatically fails Strength and Dexterity saving throws.
- Attack rolls against the creature have advantage.
Incapacitated
- An incapacitated creature can’t take actions or reactions.
Even though neither condition states that checks are made with disadvantage, our DM ruled to roll Initiative with a disadvantage since they can't move or take actions. This made sense to all of us, but we are wondering what the ruling by RAW is.