Non-full blocks are behaving strangely on my server this snapshot. 

When walking on path blocks, soul sand, farmland, etc. that is neighbored by an air block, water block, slab, etc. will create an effect such that the non-full block is like a magnet with the same polarity and tries to push the player off toward the air, water, slab, etc.

Examples of situations this can happen: When walking on farmland parallel to water, the water behaves like a magnet and pulls the player in.

Additionally, when trying to fight the magnet, the path/farmland blocks have loads of particle effects beneath the feet. I have noticed this especially when walking up slabs onto the path blocks and jumping from one path block up one block to another path block.