I use DAVx5 3.3.1-ose in Samsung Galaxy S5 Plus (SM-G901F), LineageOS for microG 16 (Android 9).
I sync address book and calendar with a Radicale 3.0.6 server locally on my notebook (Windows 10 Professional 64 bit) via the hotspot of the notebook.
As I do syncing not constantly automatic sync is deactivated on the phone, I sync manually.
Syncing the address book works flawless. Writing new/changed events from the server to the phone also. But to write events from the phone to the server I need to tap the sync button twice. The first sync runs for a moment but nothing is written to the server. The second sync then writes the events to the server as expected.
There is no difference whether I use the sync button in phone account settings, on DAVx5 start page or the separate buttons for address book and calendar.
Is this an issue of DAVx5, the Radicale server or the phone itself?
(The log is from previous DAVx5 version, but nothing changed since)