  The internal gravity modes of the Sun are notoriously difficult to detect,
and the claimed detection of gravity modes presented in Fossat et al. 2017 is
thus very exciting. Given the importance of these modes for understanding solar
structure and dynamics, the results must be robust. While Fossat et al. 2017
described their method and parameter choices in detail, the sensitivity of
their results to several parameters were not presented. Therefore, we test the
sensitivity to a selection of them. The most concerning result is that the
detection vanishes when we adjust the start time of the 16.5 year velocity time
series by a few hours. We conclude that this reported detection of gravity
modes is extremely fragile and should be treated with utmost caution.
