Fatal PHP errors in WPMU DEV Dashboard 3.1.1

I’m getting the following error in a few different places (line numbers and files are sometimes different):

Fatal error: Cannot use string offset as an array in /path/to/wp-content/plugins/wpmudev-updates/update-notifications.php on line 1156

In one location I noticed the string being returned was a serialized array, so I unserialized it and the error went away in that particular location, but obviously this is an issue elsewhere as well. I need help with this ASAP.

Thanks in advance.