I've been using the Add New Users plug in for several days. Starting last night, it started hanging. It froze and didn't add 3 of the 15 names.
Today, it froze and added all the names to the wp-users table, but NOT the wp_m_membership_relationships table.
The page has been 'loading' now for about 20 minutes. No data is actually being processed and nothing is being transferred to the membership table. It's just hung.