When I place a block, it sometimes doesn't get placed, but I don't have it in my inventory. This also happens with Water Buckets. I tried this Technique, where I place water, swim it up, remove it, and place it a bit higher, and then swim up, to get all the way up a hole in the ground. I did it, and after about 3-5 times placing the bucket, I placed it, and no water got placed, and I had an empty bucket.