Ah I see. It looks that might be due to the exceptionally long selector MT is suggesting. I should be able to fix that be setting a max-width on the list. I’ll update you when an update is ready, hopefully later today.
I’ve just released version 188.8.131.52 which sets a max-width on the list sizes. This may not necessary fix your issue however. If not, would you mind sending access details for the affected site via our secure contact form?