Please show the paragraph settings of the left side paragraphs.
All paragraphs on the spread were set up "as allign to grid". The grid is 14 pt, and interline of paragraphs is 14 pt too. Offset of all text frame option is set up to Leading (it is not important for this test).
I moved one line from first to second frame using keep options, and the set up vertical justification to the left frame of the spread.
Next I place the cursor to the right page on the first paragraph (this one which is going through the spread) and change it to the paragraph style without align to grid.
I have tested this problem many times in my old works made in CS 6 and now InD CC 2015 allways do the same bug.
The problem is biger if you change the paragaph style which is going form the right page to the next left page. Then you could't see this bug at all.
Provide us a link to that document.
After making an Object style and making another one, applying the other object style and reapplying the object style with your settings heals the problem.
You should never work without object styles.
I can heals the problem withot object styles.
In a book with one thread you want to use object styles?
How woud you like to define vertical jusification as an object style to the on frame of the thread which do not have vertical justification?
It is not a problem of the object styes. It is a problem because of the new footnote feature which adobe made in CC. In my opinion it is a bug.
In InDeisgn CS6 it was working perfect.
See my topic about inline footnotes in CC 2014.
If you run the "Recompose all stories" command, everything is fixed (Quick Apply > Recompose all Stories).
I use styles for everything. Why not using Object Styles in a single thread? Not even one reason exists not to use them.