scaffolding doesn't work on the edge of scaffolding

the video i attached says 19w08b but i have tested both versions and it is an issue. in fact, all of the versions with scaffolding i tested had the issue. as you will see in the video, i go to the top of a scaffolding tower (doesn't matter how high) and i place a block on top of it. I jump on that block and hold shift until the end of the block, i break it and when i push shift to descend through the scaffolding i actually fall, if i stop holding shift i will stop on a scaffolding block and sustain fall damage. when i push the spacebar to ascend i jump on each level instead of the usual smooth movement upward. here is a link to the video on google 

https://drive.google.com/file/d/1fEWjWzDzv9PRNADfOm688lCVbkijmmt7/view?usp=sharing