Currently running into a problem using VSVim and Visual assist where I can no longer use "Find All References" after opening a split screen with the ':vs' command.
The error I get is that 'Find References is not available because the symbol is unrecognized'.
The steps to reproduce are: 1) Open file in Visual Studio 2) Verify find references are working. 3) Split the screen through the ':vs' command. 4) Check find references again.
The same occurs with ':split' but only after quitting from one of the windows.
That is, a little weird. I've nearly always been using the :vs command with VsVim but as you say, it's not in the support feature list. <C-w>v and <C-w>s are supported, which do the same splitting but they actually seem to work with visual assist.
I can only assume that I have some vim setting somewhere which is doing some sillyness, but I don't think this is a visual assist problem.
At a wild guess, you had or have a mapping in your .vimrc file for ":vs". It's years since I have played properly with a .vimrc file, but if memory serves correctly this is the sort of thing you could fairly easily do. If so, changing what this command triggers should help.