I am receiving the same LinTerp warning message using version 6.42 with ARR2016 ensemble events with initial losses varying by ARI. The messages seem to appear when the simulation reaches an ARI where the initial loss factor is greater than 1. The batch.out indicates “Error interpolating initial loss factor, ARI factor set to 1.0”. The storm files confirm that the initial loss factor was set to 1 instead of the value specified. This has occurred in two separate models that have been updated to ARR2016 hydrology. Workaround at the moment is to run in separate batches where initial losses remain constant across ARI’s.