I've been validating manually after a backup. Is there a way to do this automatically? I'd like to do both steps overnight.
Yes, validation can be an automatic part of the backup. As editing an existing task often produces unexpected results, I would suggest you start a new task pointing to a new sub-folder so prior backups are not mixed.
The validation option is part of the backup options and be sure that monthly validation is not selected.
My illustration relates to the validation occurring immediately following the backup and not at any other time.
Check figure 12 within this link. Have you checked the log file (for that specific backup) for an explanation
When you choose the schedule for the validation, under all the options in the advanced schedule options. It is possible that the validation doesn't happen because it is waiting for the computer to be "idle". Unticking these boxes also avoids the "operations are in progress" type of behavior on shutdown.