In rare circumstances, th
e iPhone GPS has failed to operate with the LTE network. While this may be a one-off occurrence, some users have discovered a correlation between GPS and network choices, as they were able to cure the problem by switching from LTE to 3G. As a result, you might as well attempt this workaround on your own and see what occurs.
To do so, navigate to Settings-> Cellular-> Data Options-> Voice & Data-> 3G from the drop-down menu. Restart your iPhone after making the modifications to the data options settings, and then check to see whether GPS is working properly.