It's possible that this upstream PostgreSQL issue affected you. What is known for sure is that there was a bugfix for GIN, that just missed the latest round of point releases. See:
This fix alone could have made all the difference here (though this is a guess). I assume you won't have this fix with Aurora just yet (not sure -- I don't work for Amazon). But, I'd mention this to AWS support if it seems at all relevant. Hopefully they'll get in touch with the community if that's what it is.
https://postgr.es/m/CAH2-Wz=GTnAPzEEZqYELOv3h1Fxpo5xhMrBP6aM...
It's possible that this upstream PostgreSQL issue affected you. What is known for sure is that there was a bugfix for GIN, that just missed the latest round of point releases. See:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit...
This fix alone could have made all the difference here (though this is a guess). I assume you won't have this fix with Aurora just yet (not sure -- I don't work for Amazon). But, I'd mention this to AWS support if it seems at all relevant. Hopefully they'll get in touch with the community if that's what it is.
Good luck