One of the biggest contributors to issues with an account is devices running versions of the software that are out of date. In order to minimize future disruptions, we updated the pinned SSL Certificates in the backup apps in Feb. 2019 with version 7.5.0. Older versions of One and Groups use the older SSL certs which are now invalid. What this means is that those older versions no longer communicate properly with the server or with the current version of the software on other devices. This causes a wide variety of issues. These issues are not limited to the devices that are out of date and are often account wide.
Password propagation is a big issue with out of date devices. There's nothing wrong with your password, the out of date devices just cause it not to be communicated properly to your account.
Uploads can be excruciatingly slow, or stop completely.
As with uploads. They can be extremely slow, stall out, or just never start at all.
Syncs and Shares
Because communication between devices and the server as well as devices with each other is damaged by the devices being out of date, syncs and shares are often effected or stop working entirely.
Another frequent occurrence with out of date devices is the account reading as disconnected even when it's not.
There are solutions to this, depending on your need of the devices and the data associated with them.