Client Side Problems with Block Calculation of Mushroom Blocks

So, I have found a slight problem, I am developing a resource pack for my server and I came to the mushroom blocks in 1.13 Java edition. The block calculations on client side propagate in z direction only for red mushroom blocks and in y direction for brown mushroom blocks. Me and a plug-in developer believe it to be a bug. We are trying to use each block state for our benefit and to allocate a texture to each block state to maximize the amount of "blocks" we can have in our Resource Pack / Texture Pack. We are of course able to do this, however when using these blocks in-game "bugs" arise. It gets more and more confusing. In some cases the client calculations spread a bit more that just along one line. But I don't understand the conditions. To the client the blocks actually change blockstate (and texture in-game), however to all other clients it remains the same and when you relog it appears all normal. Thanks again if you you can help!

 

Below is an image of what I am talking about, the block alone in the middle is the same block used for all those another patterns. However you see they changed state when put next to each other.