I don't know if anything has changed in the rules for class K and class S.
I was recently checking my own Prsi record back for a few years to get information about the time of year when different sources of earnings related prsi were added in.
I have 2 sources of class S Prsi.
From an ARF and from unearned investment income.
It seems that the class S for the ARF shows on my record in April each year.
The class S for the unearned income doesn't show until into December each year.
Your rental unearned income Prsi probably won't show on your record until December.
It's strange that currently there is class S showing for 2023 on your record.
I checked my 2023 Prsi record now and it is not yet showing the class S for the unearned investment income. I have 52S now and when the unearned income shows this changes to 104S
You should check your record at the end of 2024 or early 2025 to see what shows then.
Let me know what happens. I would be interested to see the final outcome.