Yes the Previewer is not the best representation and is really best for testing quick, simple functionality. For more accurate testing I always use the Share option and install to my phone, or go ahead and push to Testflight/Google Beta test to get a better idea of what the final product will be.
It did the work for most of the stuff, but I guess QR scanner really needs the GOogle Beta TEst. BUt I can already see much better and test the app with the share option. Thank you very much.