The beta version is a separate install - unless you reinstall the plugins, and they have been set up to go to the beta as well as the release build, they won’t be available in the beta. same for shaders. That doesn’t, however, explain the issue with Reality in the release version.
Is there a way to configure DIM to automatically keep plugins up to date for both the beta and release?
If both the beta and the release existed at the time of install and were installed by DIM, DIM will install what needs to be installed to both. If you did not have both, but now do, the best thing to do is uninstall and re-install the plug-ins in DIM again. Afterwards they should be updated correctly.