My 50 FPS footage automatically converted to 24FPS by DaVinci Resolve
This is related to your default Project timeline framerate.

As soon as you add your first timeline to the Project the Project timeline framerate gets locked, and when you add subsequent imported media it will inherit the same playback framerate as the timeline.

If you start a new Project and first add a New Timeline - it will lock to the Project default timeline framerate.

If you start a new Project and first import Video media with a different framerate to the Project timeline default - it will ask you if you wish to change framerate to match the media, and then lock the timeline framerate.

So probably best to set your framerate on a new Project before you start editing in: Project Settings > Master Settings > Timeline frame rate 

You can also create default/loadable settings in: Project Settings > Presets