/tick command doesn't work outside of the console command line, putting it in a command block or .mcfunction file always produces a syntax error.
How to reproduce:
Place a command block containing "tick rate 100"
Trigger the command block and query the tickrate
Nothing changed, command block displays an unspecified syntax error
Linked issues
Comments 3
Sorry, realized that a few minutes ago. The empty syntax error is still weird though, so I'm going to leave the report up in case that is not intended.
Duplicate of MC-128155 then.
This is working as intended, see the change log: