Hi, Annette. The technology around making dried yeasts has changed so that the particles are smaller and have fewer dead cells around them than they used to; there may not be enough structure there to hold any carbon dioxide bubbles that are produced. You could always put a couple of tablespoons of the flour in the recipe into your proofing mixture, which would give you a better display if your yeast is working well (which it seems to be doing from your description). Susan

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