I reported this bug but https://bugs.mojang.com/browse/MC-123311 so mine was duplicate
https://bugs.mojang.com/browse/MC-123311 is said that it is fixed but it is not yet
edit even the rail bug originally from that bug isn't fixed yet
Bug stair: https://imgur.com/jcjT7q0
Bug rail: https://imgur.com/onBgND9
MC-123922
stair block does not update after retracted with piston
Resolved
Duplicate
0
BBLZ
(Unassigned)
Unconfirmed
Minecraft 18w01a
Retrieved
Thanks, turns out I misresolved that ticket.
Please comment on the ticket in the future if you want it to be reopened instead of creating a new one.