Grafana 8.1: why set right_y no effect?

many lines were shown on a panel and then I set one of them to use right y axis and others use left y axis as below:
but I find no effect.

I have recently (in v8.1) observed the same thing, where I was trying to get a calculated value (from a separate query) on the right axis. I think I got it to work by clicking back to the query, changing the graph, toggling the legend, etc. Try turning on/off various options and see if you can get it to appear (sorry that I cannot be more specific, but I know this same thing happened to me a week ago and I got it to eventually work).

thanks again, grant2