Keep an eye on complex buildings. Especial the high rise (multi story) buildings and buildings which shows their side views  as well. Check this footage how to map these buildings 
https://www.youtube.com/watch?v=dsfUcslLtVc
https://drive.google.com/file/d/13RTwH7sChRWrG5bIjysF2ripBgh3F5l4/view?usp=sharing 
And,  solve the issues shown on the issue triangle before you upload your mappings.
Best regards and keep mapping
