That happens if the system does not converge, i.e. has loops that do not converge, and this can be if you change parameters so that e.g. out of 1 kg material 1.5 kg material is created. The results then become infinitely high (and don't make sense); the calculation libraries throw error messages, but for now, these messages are not passed to the openLCA log file. We are working on passing these in the next version to become more transparent, FYI.