May 10 2021
I'm affected by this too. I recommend assigning it a high priority. By not being able to see IP's on one's watchlist, there is possibly a lot of vandalism and poor edits going undetected.
Feb 22 2021
I support raising the priority of this. Mobile IP users not being able to see user talk messages is a big deal on en-wiki. We use warning templates all the time. If they can't see the messages, then they can't fix their behavior, resulting in needless extra vandalism, warning templates, AIAV filings, blocks, and time expended.