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I know that you may not want to post this, but the URL of the site would help. Generally speaking, Google will sometimes decide to use all kinds of alternative information about your site if Google deems that this is "better for the user".  As you may know, Google will show different title tags and descriptions in the SERPs, if it feels that is more appropriate. That said, this is pretty major with Google changing the domain name. As it looks like your .co.uk is being chosen vs the .com it seems like Google feels like the .co.uk is the better "local" version for this audience.  Is your audience in the UK? Did you change anything in Search Console to indicate that the .co.uk site is the preferred site for a UK audience? You need to look at any and all signals that you are giving to Google and see if any of them contradict what your 301s are showing. Here is what I would look at Manually go through the 301s. Use a tool via your browser or a website that will show you what is happening in the 301. The 301s might actually be 302s (and that would explain a lot). Use the site: command in Google.  See what is indexed and what is not. Check the serps for the KWs that are ranking.  Click through them and see if you notice anything strange Run a spider on all the .com and .co.uk URLs.  Is there some sort of strange canonical setup that you do not know about? Did you do something funky with the href langs? Are the redirects 302 or maybe taking 2 and 3 strange hops? Check google search console.  You should have accounts for both domains, even though you only have 1 site active. If not, get an account setup for each domain. What is Google showing you? Do you have any strange stuff in xml sitemaps?  What about robots.txt? Double check with your devs that "nothing" has been done recently.  You might be surprised. Good luck!