As I said before, Oxygen updater is not officially supported by oneplus. You can follow the OTA survival instructions in OP, they work because you temporarily unroot before OTA.
See below - this was from them;
That's incorrect, though I think you just worded it wrong. The app downloads official updates directly from OnePlus (or Google) servers.I'm told that you don't get them directly from oneplus and you have to get it from someone else ?
I don't get their using google servers - they wouldn't be above deliberately causing delays, while their phones get good service.