We have found a serious problem with JSON_VALUE which apparently was partially fixed in 10.2.16. Specifically we're extracting a Date from JSON and if that extraction is in a function it does not work.
ERROR: Truncated incorrect datetime value: '2018-07-26T00:00:00+03:00'
If the extraction is done from the query (ie no function that does it) then it works fine.
Please see the following example: