Go into the details panel of the SM and check ‘Is emissive light source’, and then go into Post-process settings and crank the ‘Lumen scene detail’ up. Lumen culls small objects to keep the surface cache performant, which is great for dynamic world performance but means archviz requires some setting tweaking. Increasing the lumen scene detail will tell the surface cache to include smaller objects in GI, as otherwise it only has SSGI to fall back on, hence your view-dependant lighting. The ‘is emissive light source’ similarly tells lumen not to cull small emissives contributing to scene lighting.