Many owners of the recently released G-Shock Gulfmaster GWN-Q1000-1A are reporting a serious problem with the watch in which the hour and/or minute hands do not return to the correct position after sensor mode or using the hand shift function. For this reason, we recommend buying this model from an authorized Casio reseller so that you are covered with a 1-year Casio warranty and can send the watch in for a free repair. If you buy it from third-party sellers make sure they offer a good return policy. Some owners are reporting that their GWN-Q1000 does not have this problem, so apparently not every single unit is affected.
Read first-hand accounts about this problem at Watchuseek.
Update: It was reported that Casio America offered to fix defective GWN-Q1000 models free of charge even to those who bought the watch from unauthorized third-party sellers without a warranty. (Update: Though Casio America never officially announced such an offer, some users who responded to a forum post by Casio America offering support reported that this was the case. Please see the links in the comments below.)
It was also reported by Joakim Agren that Japanese retailers received a notice from Casio in April 2017 stating that this problem had been resolved.
A video of the problem has been posted to YouTube by premieroutdoors:
Note: This problem is specific to the Gulfmaster GWN-Q1000 with the water depth meter and does not affect the previous generation Gulfmaster GWN-1000.