Comment 6 for bug 1259812

I actually have an similar problem.

I have bind `g:UltiSnipsJumpForwardTrigger` and `g:UltiSnipsJumpBackwardTrigger` to `<tab>` and `<s-tab>`. But `<c-j>` and `<c-k>` still works. I actually used to have `<c-k>` for special characters that can be found in `:digraphs`.

I've also installed it from the GitHub mirror with Vundle.

vimrc: https://github.com/alex-ross/dotfiles/blob/9689bc4faa3f958359d0fedcac42798e3a33f136/vimrc
ultisnips settings: https://github.com/alex-ross/dotfiles/blob/9689bc4faa3f958359d0fedcac42798e3a33f136/vim/plugin/settings/UltiSnips.vim

Outputs
From `:verbose imap <s-tab>`:
i <S-Tab> * <C-R>=UltiSnips_JumpBackwards()<CR>
        Last set from ~/.dotfiles/vim/bundle/ultisnips/plugin/UltiSnips.vim

From `:verbose imap <c-k>`:
i <C-K> * <C-R>=UltiSnips_JumpBackwards()<CR>
        Last set from ~/.dotfiles/vim/bundle/ultisnips/plugin/UltiSnips.vim

From `:verbose imap <c-j>`:
i <NL> * <C-R>=UltiSnips_JumpForwards()<CR>
        Last set from ~/.dotfiles/vim/bundle/ultisnips/plugin/UltiSnips.vim