Power UP t.set('board', 'shared', k, v) always returns 409

Browser affected: Chrome
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I have an odd scenario where calls to t.set('board', 'shared', obj) are consistently failing with a 409 response:

This call to t.set is made after receiving a response from our API. It is the only call made to set shared data. The other response from pluginData in the screenshot above is a successful t.set('member', 'private') call.

Writing shared board data is the only thing that seems to be affected. The shared values persist in memory, but upon refresh they are gone. I am guessing because of the 409 received prior.

Oddly enough, I can get the shared values to stick when calling in response to a button click in the power up. When I make them in response to a successful post request to our API it seems to fail.