You need an Isabella with high corruption.
I just tested and no problem on my end, anyone else experiencing this?
She and a couple other chars were not actually made by me. They were made by a friend who's no longer among us, that's why I haven't been too eager to use her.
You don't need to delete anything unless you used Unren or some other decompyler... Or if you used the v97 fix...
Did you use the previous version fix?
Only a "controlled" Alma will show up on that scene. But the text shouldn't say she is...

I'll look into it
PS: Yup, the issue is the text it should say "As you and Koneko enter the baths you see that Mida is there."

Weird, can I have a sample save?