Instances for the probabilistic orienteering problem, in which each customer is present only with a given probability, from Angelelli, Archetti, Filippi and Vindigni, distributed through VRP-REP.
E. Angelelli, C. Archetti, C. Filippi, M. Vindigni (2017). The probabilistic orienteering problem. Computers & Operations Research 81, 269-281. doi:10.1016/j.cor.2016.12.025