Even I was facing this issue few days backs, I am not sure how to fix
it. But I have a workaround for you. Create an audience with query
parameter condition eg: Url should contain ?targetDebug=true, now make
choose this the audience for your experiment. you can take the target
experiement live and test it in production, whichever experience you
want to check make the traffic for that experience 100% Hope this helps.