This issue is basically identical to (which is marked as duplicate and closed, but in my humble opinion is different from HHH-10865), and in fact on 5.2.2 my testcase fails, although it was fixed in 5.2.1.
I could not upload my test-case to HHH-10866, so I open this issue.
As far as I understand it, describes it very well: Update only occurs if all lazy properties are initialized, including e.g. collections.
This is what my self-contained test case shows: The lazy property longText is not updated unless the OneToMany collection children is loaded.
JPA, Java 8, Oracle/H2