OK - so I don't know what has just happened with the latest update of Adobe After Effects - BUT - having just updated to 2015.3 (version 13.8.1) I have got some very weird behaviour. Primarily After Effects is now not correctly seeing the alpha channels of some previously imported .mov files. Just yesterday I was happily using these PNG codec .mov files - with built in alpha channel - and they were working perfectly. But now it is as if they are set to around 10% opacity, which they are not! Plus they have undergone a colour shift towards a kind of ghostly blue. All very strange. SO I have just installed the previous version of 2015 onto my system to try to get back to a version of AE that allows me to use these video clips - especially as I am mid-project! If you have a similar problem and you don't know how to install a previous version, of any Adobe product, using your Creative Cloud subscription, I will write another blog post shortly, explaining how to do that. But right now I have to test my new install to ensure I can render out what my client needs!