This has compiled Bootstrap 4 files with flexbox-mode enabled.
npm i -S bootstrap-flexbox-static- Then, within your project, just reference the compiled files from
node_modules/bootstrap-flexbox-static/dist.
I take 0 credit for the amazing work done to create Bootstrap, I've simply compiled what they have built.
It's highly unlikely this project is the source of any bugs, and they should instead be filed against https://github.com/twbs/bootstrap/