OK, I tried your save and managed to do it.
There's an additional condition to progress in Midnight Bath #2 : you need to have completed Rachel's star in In Need of Attention.
To do that from your save : Do nothing of the day. Advance until midnight. Go in Emily's room then in Chloe's room. You'll get the first 2 stars. Go to bed
The following day, do nothing of the day again. Advance until midnight. You should find Rachel by the pool. Do not talk to her. Go to the Corridor, then in Rachel's room. You'll get the last star of In need of attention. Immediately go to the pool. You'll have the option dialog to continue Midnight Bath #2