Speak Text bug with Siri voice: "South Korea" mispronounced & words in quotes ignored

I'm using the Speak Text function on my MacBook Pro (M4 Max, macOS 26.3.1) with the Siri voice. I've encountered two consistent issues:

1. It mispronounces "South Korea."
2. It completely ignores single words that are enclosed in quotes.

The problem goes away immediately if I switch to any other voice (like Samantha or Alex). I want to use the Siri voice because it's the best, but these glitches make it difficult.

I have already tested this on a brand new user account, and the problem persists, so it doesn't seem to be a setting in my main profile.

Has anyone else experienced this with the Siri voice? Are there any known workarounds or fixes? I have tried adding a pronunciation for South Korea