Productivity modules in furnaces

[Frightning]

So there is a very serious issue affecting productivity modules in (electric) furnaces: If at any point, the furnace has consumed all of its incoming ore and is waiting for more, all progress toward the next extra product is lost. This severely penalizes underfed furnaces effectively stripping them of all the benefits of having productivity modules in them and needs to be fixed. I suspect it has to do with the fact that furnaces 'auto-detect' what was put in them and automatically select the only applicable recipe (hence you can never 'set' the recipe explicitly, and thus it forgets what recipe it was making progress towards an extra product with and thus loses the progress it had made).

Edit: So upon further testing, it appears that, although the progress bar disappears when it runs out of ore to smelt, it does however still remember the progress it had made towards an extra product. How did I not notice this before?? *facepalm*