I have the same problem on 1.7.2 and I think I have something that might help. I compared rgl_log file for loading vlandia_town_e (Rovalt) and the rgl_log file for a city map I've made, which besides the missing flora works fine. Here's the section of the log file for vlandia_town_e:Forwarded to the QA team for further investigation. We will reach out again if we need more information. Thanks for reporting and sorry for any inconvenience!
[19:36:31.706] Scene_view::clear_all(Main_map)
[19:36:31.843] Loading xml file: $BASE/Modules/SandBoxCore/SceneObj/vlandia_town_e/scene.xscene.
[19:36:36.184] Loading xml file: $BASE/Modules/SandBoxCore/SceneObj/vlandia_town_e/atmosphere.xml.
[19:36:36.343] Granite Warning: W1005: Performance warning: A tile needs to be uploaded to a MipmapStreamingTexture with more than 256 redirects.
[19:36:36.523] Oro temporary memory watermark: 5.25 KB (max 256 KB).
[19:36:36.559] 1801 entities are registered as oro.
[19:36:36.812] rglShader_manager::read_compressed_shader_cache_package : 0.000131
[19:36:36.855] Placed tree count, 14299, shrub__mix
[19:36:36.879] Placed flora count, 15877, flora_grass_a_non_shadow
[19:36:36.899] Placed flora count, 35990, flora_grass_a_non_shadow
[19:36:36.932] Placed tree count, 132135, tree_high__mix_pine
[19:36:39.760] Loading xml file: ../../Modules/Native/Atmospheres/Interpolated/semicloudy_vlandia.xml.
[19:36:39.910] {[LOADING DEBUG] setup_battle_scene_Imp ended
[19:40:11.603] Scene_view::clear_all(Main_map)
[19:40:11.734] Loading xml file: $BASE/Modules/DellarteDellaGuerraScenes/SceneObj/dadg_dover_with_cliffs/scene.xscene.
[19:40:11.740] Loading xml file: $BASE/Modules/DellarteDellaGuerraScenes/SceneObj/dadg_dover_with_cliffs/atmosphere.xml.
[19:40:11.966] Granite Warning: W1005: Performance warning: A tile needs to be uploaded to a MipmapStreamingTexture with more than 256 redirects.
[19:40:12.148] Oro temporary memory watermark: 32.63 KB (max 256 KB).
[19:40:12.210] 1709 entities are registered as oro.
[19:40:12.854] rglShader_manager::read_compressed_shader_cache_package : 0.000081
[19:40:12.854] Missing shader from sack: pbr_terrain
[19:40:12.854] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.854] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.854] Missing shader from sack: pbr_terrain_shadowmap
[19:40:12.854] Missing shader from sack: pbr_terrain_pointlight
[19:40:12.860] Missing shader from sack: pbr_terrain
[19:40:12.860] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.861] Missing shader from sack: pbr_terrain
[19:40:12.861] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.864] Missing shader from sack: pbr_terrain
[19:40:12.864] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.864] Missing shader from sack: pbr_terrain
[19:40:12.865] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.865] Missing shader from sack: pbr_terrain
[19:40:12.865] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.866] Missing shader from sack: pbr_terrain
[19:40:12.866] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.867] Missing shader from sack: pbr_terrain
[19:40:12.868] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.870] Missing shader from sack: pbr_terrain
[19:40:12.870] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.870] Missing shader from sack: pbr_terrain
[19:40:12.871] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.873] Missing shader from sack: pbr_terrain
[19:40:12.873] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.874] Missing shader from sack: pbr_terrain
[19:40:12.874] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.876] Missing shader from sack: pbr_terrain
[19:40:12.876] Missing shader from sack: pbr_terrain_gbuffer
[19:40:12.961] Placed flora count, 0, flora_grass_b_non_shadow
[19:40:12.964] Placed flora count, 0, flora_grass_b_non_shadow
[19:40:13.000] Placed flora count, 0, flora_grass_b_non_shadow
[19:40:13.079] Loading xml file: $BASE/Modules/Native//ModuleData/water_prefabs.xml.
[19:40:13.095] Loading xml file: ../../Modules/Native/Atmospheres/Interpolated/semicloudy_vlandia.xml.
[19:40:13.228] {[LOADING DEBUG] setup_battle_scene_Imp ended