when i use the command /execute as @p positioned as @s ... then after the "Positioned" the "as" is an error.
this is only on realms (in my singleplayer world isn't a error with the execute command)

that error comes only after "Positioned" 
and i use the command without a "."

Reproduce:

1. Go on Realm on MC bedrock
2. Open chat and type in any /execute command with "positioned" as second chain
3. Press enter and you become an error after the "positioned" chain