Reproduce:
/execute @p ~ ~ ~ tp ~ ~1 ~

Maybe it's on purpose, but I think it should tp the person who the execute is used on.

Another similar, but bit different issue:
/spawnpoint <player> doesn't work at all.

examples:
/spawnpoint @a --> no, it tells me usage
/spawnpoint @p --> same
/spawnpoint feca1997 --> same (I thought at least this would work)

/spawnpoint and /spawnpoint @a ~ ~ ~ work as intended.