Not seeing comment replies (that I can see in post)

• I reply to a post
• OP replies to me
• Message not available in my message inbox, even under "all"

I can see that they replied to me, I can see their text, I can reply to them again, so we're not blocking each other, but their comment isn't in my inbox.

Now wondering what other replies I'm missing.

• Night mode: true
• RES Version: 5.24.8
• Browser: Firefox
• Browser Version: 144
• Cookies Enabled: true
• Reddit beta: false