I see there have been bugs in the past like this, but this one involves one sticky piston that PHYSICALLY disappears. Sometimes only part of the apparatus disappears, like my first pic (I haven't had too much success taking screenshots of this). If I stand on it I may find myself falling downwards. The hit box is gone too.
I'm seeing this with regular pistons too.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.