@sam107,
As we state very clearly in our FAQ on Ads troubleshooting, the algorithm will send you ads based on several varying factors, including your browsing tendencies, your locale/region, ad campaigns active/running in that region, and other data. Taken directly from that article:
The goal is to show you privacy respecting ads that are relevant to the user in the right context (a “match” is found) – not to make sure that all users “see some ads” . Enabling Ads does not guarantee that you’re going to see ads – if the system does not find a match for you in the ads catalog, then you will not see any (more information on this below).
Further, you may see ads appearing regularly today, but tomorrow you may not see any – and that’s perfectly fine . In this situation, it really is a feature , not a bug . We appreciate everyone’s understanding of this distinction and implore you to keep this in mind before assuming that the feature simply “isn’t working”.