Plugin hook is called only when jekyll is run without bundler

I wrote simple plugin using Jekyll hooks. My plugin is using mainly two hooks:

  • Jekyll::Hooks.register :site, :after_init do |site|
  • Jekyll::Hooks.register :documents, :post_render do |doc|

When I have project not using bundler and I run jekyll serve --trace everything works.
But when I run it in project using bundler by runnig bundle exec jekyll serve --trace only after_init hook is called.

How can I diagnose this issue ? How can I fix it ? If you need ore info write comment.

PS: This is plugin in question: GitHub - yagarea/jektex: Jekyll plugin for blazing fast server side cached LaTeX rendering with support of macros. Enjoy comfort of latex and markdown without cluttering your site with bloated javascript.

Run both with --verbose to see what Jekyll is doing.

Upgrade to new Jekyll version on both. After checking your versions of Jekyll.