Why get this warning all of a sudden?

Hi
Been using UM for a few months without any issues.. and this isn’t really an issue either but I am curious to know why I am suddenly getting this warning when I click on the users link in admin:

Warning: Invalid argument supplied for foreach() in /home/domain/public_html/mywebsite.com/wp-content/plugins/ultimate-member/admin/core/um-admin-users.php on line 157

It’s not hindering anything as it’s just a warning, but why should it suddenly occur? Not sure if it came with the latest UM plugin update or it’s something like a conflict with another plugin.

Hope someone can shine a light on this.

thanks
R

https://wordpress.org/plugins/ultimate-member/