In some places, you can't place blocks for some reason. heres a video that shows you what happend
https://www.youtube.com/watch?v=cLqKjW4vc7I
How to fix + recreate:
To fix you'll need to reload your world
To recreate.... Happends randomly, don't know how to recreat XD
That video doesn't show anything to me.
Please provide a better description and a proper video.