Board Thread:Casual Discussion/@comment-19100401-20180123011421/@comment-28980314-20180123163252

Usually that is because your neighbours have already collected the income from the buildings so you can only tap the buildings that your neighbours have not cleared yet. If you see the hand shake icon mostly over the Simpson House, Flanders House, Kwik-E-Mart, Brown House etc. it is because these buildings have a shorter time to generate income in minutes rather than hours.