RC2 was displaying everything fine. Upgraded to RC3 and the slider on the page started showing just the default placeholder images.
The setup for mine is Classic Slider with two slides, each containing a Global Block with a layout in them.
However, I tried adding a third slide with just plain text… but it still only shows two default placeholder slides on the front end.
Repro is pretty easy for this. Just add a classic slider and then try and change anything… nothing seems to get output in the builder or front end.