You think DSM 5.2-5565 has problem, but 5592 doesn't, right ?
No. XPEnology is broken. It's not a matter of DSM.
I have 5592 on a DS412+ and there it's working.
The problem is you are testing with 2 different versions. You have for the HW the actual version and for XPEnology only 5.2-5565 Update 2. If it's possible test the DS415+/DS412+ with 5.2-5565 Update 2 and see if there is also no problem.
So you can't say with 100% accuracy that XPEnology is broken. It's only an assumption.