A missing notification can mean the message never reached the app, the app did not request an alert or Android presented it quietly. Check those stages before turning every notification control on.
A completed transfer and a readable document are two different outcomes. Determine whether the file is intact, whether the receiving app supports it and whether access restrictions are involved.
When other apps work normally, start with the app that fails. A device-wide reset creates a large recovery task and may leave the original cause unexplained.
Power flowing through a cable does not prove that the cable and current connection support file transfer. Work through the cable, phone mode and receiving computer as separate checks.
Discovery problems and transfer failures are different. First make the receiving device visible through the current Quick Share controls, then test with one small non-sensitive file.
A Wi-Fi icon shows a connection to a wireless network, not proof that the entire path to a service works. A few comparisons can identify where to investigate without resetting every network setting.