Hi @aditya , I was using a special Roam command pack with additional features. For example, it would automatically put a # in front of comma-separated keywords, and it would automatically enclose multi-word keywords in double brackets. It appears that the command is broken now.
@Cedric_Debono_Blaze do you know what happened with the Roam command pack?
For other Roam users out there, this is the snippet I'm now using for keywords, which works just as well. It's just more verbose.
Keywords:: {note}{formtext: name=keywords; default=}{endnote}{repeat: for keyword in split(keywords, ",")} #[[{=trim(keyword); trim=yes}]]{endrepeat: trim=left}