Hi Sheena,
A couple of ideas since you mentioned that everything had worked prior to this week:
If you can take a look at the records that are coming through with your form, see what the "Anonymous IP" recorded is—if they're all showing up the same, you may have a problem with your reverse proxy (i.e., something like a website load balancer, an A/B tester, or a CDN) not passing the original IP through. Sadly, it's pretty common for IT departments/software providers to forget to provide accurate X-Forwarded-For headers and thus make all traffic look like it's coming from one IP.
If that's not the case—and there's no anonymous IP being recorded at all, it could be due to the way your contact requests are being set up. If you're using a web service API (or another item to push form data into Marketo), you should ensure that it's correctly passing the form data in a way that it's associating with the former anonymous record rather than making another, unconnected record upon creation. This most commonly happens with things like Gravity Forms and just requires a little due diligence.
If the IPs are being uniquely recorded and you're not seeing any inferred data, it's possible that the IPs you've seen this week simply don't have any geoIP information associated to them. This is relatively rare, but does happen—though it's far more common that the IP is just misleading (like my California cell phone showing up as a Texas/Virginia IP within CA.)
Knowing what's being recorded in that Anonymous IP field will probably do a lot to help you figure out the root cause.
