Missing something setting up a button

Thanks, after doing both steps it's all working as expected now.

For my own sanity I also tried putting my own resistor between C1 and ground instead of the internal own - probably unsurprising that works as well.

With the benefit of hindsight I can see how the solution works, but I'm a little confused as to where the signal float is coming from. Is this to do with the quality of the switch or just the way of the world and something I'll learn to live with?

Thanks again