I recently upgraded to the new version 2.1.16 which was released via NuGet and I think I found a bug with it. After updating, I'm seeing 2 strange, related issues:

1. When I added a new nugget to my code and ran the project, i18n.Postbuild.exe erased every other existing translation from my existing messages.po. What I mean is that it kept the msgid, but set the msgstr to "" for every other msgid in the file.
2. When I reverted my messages.po back to put back all of my existing translations, I ran my code and then it would only translate every entry from the messages.po. For example, I had a nugget for "Loading..." and it would not translate this no matter what. However, it would translate the next nugget no problem.

I confirmed that reverting back to 2.1.15, fixes the issue.

One thing that I suspect could be causing the issue is that we have i18n.DisableReferences set to "true". I haven't had a chance to test if we get the same results by setting it to false, but let me know if you need me to test that and I can.