Water flowing through barrier blocks

Note: I was using creative mode to do this.

Usually, I post my Minecraft builds on Instagram. When I tried to make an underwater world in a building, like one of those walk-in underwater marine things, I tried to use barrier blocks to seperate the walkway from the water. Although I covered every block possible to allow water to leak into the walkway, there seems to be a sort of bug that allows the water to flow through the block. Even when I replaced the barrier blocks with glass, water still came in. At some point, I could even walk through the glass as if I was spectating - but of course I wasn’t. It was a mess so I decided to report this to you. I hope you can fix this bug.