Alexa room groups not working – "Turn on the fan" always controls the fan in the first room

I have two Echo speakers in two different rooms.

Room 1: Echo + Fan 1

Room 2: Echo + Fan 2

Both Echo devices are assigned to their respective room groups, and each fan is also assigned only to its own room group. I want to name both fans as "fan". I dont want to use any extra syllable.

My expectation is:

Saying "Alexa, turn on the fan" to the Echo in Room 1 should turn on Fan 1.

Saying the exact same command to the Echo in Room 2 should turn on Fan 2.

However, when I say "turn on the fan" to the Echo in Room 2, it still turns on Fan 1.

I've already verified that:

Both Echo speakers are in separate room groups.

Both fans are in separate room groups.

There are no routines using the phrase "turn on the fan."

Has anyone else experienced this? Is there another setting I'm missing, or is this a limitation/bug in how Alexa resolves room-based device commands?