Using bedrock on windows 10. Operator privileges have not been working for us as well since May. Submitted a bug: https://bugs.mojang.com/browse/REALMS-1770. Mojang responded they would look into it but didn't respond back.
Thank you for your post, the workaround works for me, if the person who has operator assigned joins through a friend instead of joining directly, their operator privileges show and can be used. A silly workaround but at least we have something until this gets fixed.
See this bug report for a workaround. Same issue of players assigned operator unable to use it. https://bugs.mojang.com/browse/REALMS-2013 . Hopefully this gets fixed.