How to debug this problem with the :map command?

Question

I was trying to view my key mappings because I can't seem to jump through parts of snippets in UltiSnips.

So I type :map and hit enter and it comes up with the start of the list, but there I can't scroll down the list. When I try to, it gets glitchy at the bottom, where the bottom mapping changes but again is very glitchy.

I remember being able to scroll down this list no problem, but it appears to be broken.

How can I begin to debug this?

The plugins I am using are these:

Plugin 'justinmk/vim-syntax-extra'
Plugin 'francoiscabrol/ranger.vim'
Plugin 'flazz/vim-colorschemes'
Plugin 'felixhummel/setcolors.vim'
Plugin 'dracula/vim'
Plugin 'szw/vim-tags'
Plugin 'majutsushi/tagbar'
Plugin 'SirVer/ultisnips'
Plugin 'honza/vim-snippets'
Plugin 'jeetsukumaran/vim-buffergator'
Plugin 'vim-scripts/c.vim'
Plugin 'WolfgangMehner/latex-support'
Plugin 'Shougo/deoplete.nvim'
Plugin 'bash-support.vim'
Plugin 'tomtom/tcomment_vim'
Plugin 'dzeban/vim-log-syntax'
Plugin 'octol/vim-cpp-enhanced-highlight'
Plugin 'artur-shaik/vim-javacomplete2'
Plugin 'uiiaoo/java-syntax.vim'

Answer 1

I can scroll the result of :map using the arrow and page up and down.

However, I like to use the scriptease plugin and run:

:Verbose map

It puts the result in a buffer you can scroll but also search and filter.