For the backup stuck/timeout/not responding issue, please first try to adjust settings suggested in this doc.
You can click the Cancel button on the backup page to cancel the task. The task will be canceled after the plugin finishes backing up the current chunk, which can take few minutes in some cases. If the cancellation still does not complete, please check whether your website cron system is working properly, as WPvivid uses the cron system to cancel a backup task.
Nothing worked. I like this plugin as it allow cloud backup for free but it seems does not work because of very tight resources on shared hosting. So I want to point that unyson backup never fail and it is very fast too.