Denite has deprecated the file_old, file_point, file_rec sources and replaced them with file/old, file/point, and file/rec. Vim-devicons should support these new sources.
As a side note, I have never had icon colors work for :Denite file_rec. I'm not sure if I did something wrong or if that ever worked. I can separate that out into another issue if preferred.
VimDevIcons is the last loaded vim plugin?NVIM v0.4.0-dev0.11.0Main issue:

Note The above screenshot is using the vim "floating window" feature, but the result is the same for either way that Denite is rendered (in a split or floating window).
Colors not working in with :Denite file_rec:

Not home currently so can't make a PR, but you can add this to your config:
call denite#custom#source('file,file/rec,file/mru,file/old,file/point', 'converters', ['devicons_denite_converter'])
Thanks @ctaylo21 and @Luxed
fixed in #273
Most helpful comment
fixed in #273