ACR 30.0 running on a Samsung Galaxy S6, using Android 7.0.
I have ACR configured to upload to my private Owncloud server, only over WiFi, using WebDAV. The Owncloud server is on my internal LAN, and is also accessible via the Internet.
While searching for some particularly important calls today, I found that they weren't on Owncloud. They were available on the mobile. In fact, a call that I made today is the same - not in Owncloud, but is on Mobile. I made the call many hours ago and the device has been on WiFi the whole time. I can manually upload the call from within ACR if I use the "share" icon and choose the Owncloud app.
A look over the past year shows about 760 calls on my mobile, but only about 430 have successfully been uploaded to Owncloud.
ACR shows no uploads pending.
WebDAV upload is the sole reason I purchased a license.