I've got a bathtub upstairs that won't drain (at all), and slowly fills with water apparently from fixtures in the same bath room and the adjacent bathroom.
Whatever is going on doesn't appear to be impacting any downstairs fixtures (sinks, toilet, washing machine). I tried to snake the bath but the snake stops advancing without being able to clear the clog. It brings back small clumps of hair. I called out a solid professional plumber, and he was also not able to either clear the clog or explain the backing up.
His recommendation was to begin cutting out ceiling downstairs to get into the pipe and figure out what was going on, but I wanted some other input before I embarked on something expensive.
Is it possible that a local clog at the tub could be causing the backup? I'm obviously not a plumber, but it seems like that would have to be somewhere in the pipes shared by the two bathrooms for water to come across from the other shower into this tub.