When trying to walk up a staircase that is being retracted there is a high chance that you will fall through the staircase block. Creating this setup and continuing to hold forward when walking up the staircase will give the best results.

Observed Result:
You walk up the staircase and usually end up falling through the staircase

Expected Result:
You don't fall through the staircase and remain on top of it after it retracts