I made a Time Machine backup and then reinstalled macOS. Yesterday and this afternoon I was able to view the Time Machine backup and copy the files I wanted to keep to my clean installation.
Suddenly, the backups started showing up empty. At first I used the latest backup, but then at some point it started showing an empty Macintosh HD folder. So I moved on to the second to last backup, which was still working. Until that too began to become empty, like in this image:
I double-clicked the empty “Macintosh HD – Data” to open it, the finder window closed by itself, and poof, that backup was completely empty too. In fact, all the backups are empty… What is happening here and how do I fix it?
I’m trying my best to google it, but I can only find posts from people who see folders but can’t access them. I like this Reddit post.
I think I have the same problem as this guy, but never got an answer. Time Machine backup drive shows empty files
Additional information
When I plugged the drive in for the first time after reinstalling, I clicked on the pop-up asking if I wanted to use it as a time machine drive. This took me to the time machine preferences, where I immediately unchecked “backup automatically”, because I’m not sure if backups from a new machine will work well with those from a different machine. 
Disk utility still shows the drive is in use 
