Unexplained Changes to Company Web Activity Reporting

We use Marketo Analytics to track users that come to our site each day. Apart from page views and other metrics the most important information we collect on these anonymous website visitors is the inferred company and company fields. As long as we have used this report our data has populated correctly, but randomly starting on September 28th these two fields (inferred company and company) started only displaying IP addresses as opposed to spelling out any company names. This trend has continued through the last few days and we are wondering if anyone else has experienced this issue?