Platform: Android 8.1.0
Device: Oneplus 6 (OxygenOS 5.1.5)
Plex version: 126.96.36.19924 (b2e10411)
VPN App: ProtonVPN v1.2.2
Problem: When using the camera upload feature with a VPN enabled as well as "Use mobile data" disabled, Plex will refuse to upload camera data. This is most likely because it is detecting the mobile data connectivity situation using a slightly outdated API which does not support VPN information on what type of underlying data source is being used. It is also possible the VPN app is not setting the correct underlying networks using setUnderlyingNetworks().
Additional Improvement: Plex should notify the user why the sync has failed when manually started, rather than silently failing.