User roles issue with import

I used BackupBuddy to migrate a single dev site into a multisite network (like I have done dozens of times before), and ran into some issues that are reproduced in importing– a bug that will be fixed in the next BUB release. The first one I have solved: the imported site redirected to the dev site URL.

Now I’m having some problems with user roles that I could use some help untangling. Here’s what’s going on:

• When adding new users to the site, the drop-down for selecting their user role is squished together, and I am unable to select a user role for them. Thinking I would be able to change the user role on the Users page of the dashboard, I went ahead and added them.
• The new users do not appear on the Users page. There is an error message that appears above the users area: https://tinyurl.com/mc4odwf
• The new users DO appear in the database, although their wp_site#_capabilities are “a:0:{}”. I tried giving these users the capabilities “a:1:{s:6:”editor”;b:1;}” (what other editor level users on other subsites seem to have), but that did not fix this problem.

I’ve checked, and this issue is not appearing on any other sites in the network.

I am using the plugin User Role Editor (network activated) in order to give Editor level users the capability manage_theme_options, which lets them edit the widgets & menus. Thinking that might be part of the problem, I deactivated the plugin, but the issue remained.

I also deactivate all the plugins in this site, but no dice.

Thinking perhaps it was related to the theme somehow, I have switched over to Twenty Fourteen, but still have the issue.

Ideas for where to look in fixing this problem?