Outline reconfigures title: subtitle

I have had titles that included a word, a colon and a phrase, followed by a detailed subtitle that picks up the key words. The Book Outline fields are consistently interpreting the colon as the divider between the title and subtitle. After I’ve generated the Outline, I see that my phrase that was after the title’s colon has been moved to the Subtitle field, and the detailed subtitle that I painstakingly created is gone.
For example, if I want my title to be Potted Gardening: Nature in the City, followed by a subtitle that details the benefits, I should be able to use that without the system altering it.
I shouldn’t have to know about this “feature” that’s not intuitive and remember to omit the colon from the title as a work-around. Please remove the code that is doing this.

Thanks,
Ann Neel