Its always bugged me that you cant mix static lighting with lumen. I honestly cant think of why that would even be the case. Ive been working on this game that we really want to make use of lumen with but at the same time having the entire game use dynamic lights is super spooky.
Support for Lumen reflections is planned (supposedly)
Afaik you won’t ever be able to mix Lumen GI with static GI.