Quick -how to remove occlusion:

1. Open CW, make sure to enable two checkboxes Enable Mods and Enable DLC and select your custom DLC in DLC Level:

2. Go to Selection tab and select Mouse select (right click) checkbox and select Mode: Occlusion
Blue box frames will show up. Select box inside building (not box for whole area but inside building)

3. When selected, name of occlusion ymap will show up:

4. Select Tools... and RPF Explorer...
5. Enable Edit mode and search for that ymap name:

6. Now open ymap and search for exact values like under Box tab:

7. Rmove selected values in ymap and do same for all selected boxes inside building (some buildings got few occlusion boxes) then save ymap and replace vanilla ymap with this edited one (make sure in mods folder)

Done.