Cant place a conduit on the sides of blocks in my realm.

I can not place conduit on the sides of blocks in my realm.

What I expected to happen was...:
I expected the conduit to be placed as it has before

What actually happened was...:
The conduit refused to be placed until i tried placing it on top of a block instead.

Steps to Reproduce:
1. I built the frame out of prismarine
2. placed a block against the frame so i could position the conduit
3. Tried and failed to place the conduit for about 30 seconds straight

4. Moved the block from the side to the bottom of the frame 

5.placed the conduit on top of that block

6. removed block to finally make working conduit