According to Fujifilm, “We have confirmed that X-Pro2 with the upgraded firmware (ver.4.00) released on Dec 22 2017 stops working in certain settings. We deeply apologize for your inconvenience this may cause. […] We are preparing a revised firmware as a solution and plan to release it as soon as possible.”
That being said if you do own the X-Pro2, take note that the lock up only occurs under certain settings. According to Fujifilm, this will happen if your camera’s image quality is set to “FINE+RAW or NORMAL + RAW”; under RAW recording you have set it to “LOSSLESS COMPRESSED”; and under Drive you have selected any of the advanced filters.
Fujifilm points out that the lock up only occurs when all three conditions are met and the camera’s firmware has been updated to 4.00, which means that this isn’t something that users will experience out of the box, and that the number of users who are experiencing this issue should be quite small.