Hi @leaf,
I expect this is an issue with mavproxy configuration in Companion. I would need to look more into it to find the cause and a potential fix, but are you able to use BlueOS instead? Companion is no longer being developed, so we recommend switching to BlueOS unless your application requires one of the small number of features that is not yet implemented.
I’ve just tested, and didn’t have any issues requesting a given interval for the SCALED_IMU2 message when using BlueOS 