As the post that Esferobite linked to points out, a quick and easy workaround until bug gets fixed is to hide the preview time indicator in the timeline. The easiest way to do that is to press the ` (tilde) key over the composition panel to make it full screen.
The reason that works, what the bug is, and what Adobe's doing about it are mentioned in the post that's been linked.
Thanks a lot for your words.
I spoke to an Adobe's support CSA and he said that this is a known bug and told me to download AE CC 2014 from the Creative Cloud application (the one that sits in your menu bar) > Apps > Find Additional Apps > (at the bottom in blue) View Previous Versions. There you will see all the apps. If you click "install" you can see the previous versions to DL.
I have checked and confirmed AE CC 2014 RAM Preview works.