if you set up scaffolding such that your feet are in a block of air and your head is in a block of scaffolding, then jump, the scaffolding will stop your jump momentum partway through, then send you back downwards, making you unable to climb on. using commands to get a floating scaffold with [bottom=false] blockdata, it will not cancel your jump, and you will climb it normally once you get far enough inside it.
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However, we are already tracking this issue, and this report is a Duplicate of MC-143264, which is a report that has not been resolved yet.
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