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Steemify is more of a consumer in this regard, but @fulltimegeek, what encoding are you using and how do you sign your transaction?

The problem was I wasn't converting the operation id (39) to hex.

what encoding are you using and how do you sign your transaction?

I'm encoding the strings with UTF-8 and using my own Java lib for signing.

Thanks for stopping by @bennierex and trying to help a nerd in distress :)

Glad you figured it out!