A prospect has replied but I can't find the answer in my inbox?

It says 'Responded' but there is nothing in my inbox.

Start by looking in your spam box or in the trash folder. 

Another reason could be that the prospect has forwarded the message to another person within the company which in turn our bot can register as a reply even though technically there are no replies in your inbox from the original prospect.

Try searching for the domain or company name in the search field in your email-client.