I recently experimented with publishing a site for three different countries in the same language (choose US, Canada and GB, e.g.) under three cTLDs (e.g. example.us / example.ca / example.co.uk) using hreflang-annotation.
GSC shows no errors about hreflang, third-party-tools go fine as well but what Google is doing is indexing just one content and displaying it with different url in targeted market. E.g. using the example.us content and displaying it with example.ca URL for Google CA and sometimes even just indexing one country version and not indexing and showing it for other countries.
Has anyone experienced this as well and maybe even found a solution for telling Google to display the right content and not just the right url for a targeted country? I've seen complaints about this at Googles Webmaster Forums but haven't read about solutions yet.