Currently the Raw Digital Camera plug in does not support the Sony A7iv. Hopefully it will be updated soon?
It looks like support for that was added to libraw quite recently. We'll be updating the plugin with that, but probably during the next beta cycle, so that the new code can be tested for longer before but pushed in a stable release.
So it's not available in 12.28.2?
"In the next beta cycle" means after 12.29 is released.