This sounds like the same issue that happens with other frameworks. I believe this is a Stacks issue and is related to a stack inside a Partial that needs to reference another stack to get some settings. Often, if you re preview it will be ok. Worst case solution is to restart RW or Mac and live with it happening occasionally. It isn’t a Foundry or Potion issue.
Agreed… Although it’s the only stack that has ever done it and restarting RW or the computer has no affect. But it’s no real issue and it works perfectly every time when the partial is actually placed.