I am wondering if I am missing something that has simply become a bit more 'hidden' in M. On my old phone, which had not reached Marshmallow yet, there were, say, a dozen apps that could move a portion of their code and data to the SD card, freeing up valuable internal storage. On a new phone (Moto G2, if it matters) that has gone straight to M, I am aware of the portable storage vs adopted thing now, and I have found the Migrate option... but when I do that, it says 'this will free up 1.X Mb'. Yes, you read that right - Mb, not Gb. Apparently it is moving pretty much nothing - yet this phone has more or less the same apps on it now (possibly a couple less, but there should definitely be at least 10 apps).
Is this a casualty of the changes in M? Why can I not move the same apps over as before? Or do they require getting the
WRITE_EXTERNAL_STORAGE permission on the fly (i.e., must use them first to get it) before that is possible?
(While we're at it, why can't all apps be moved? It is my understanding that Linux / Android simply mount everything, regardless of source, as a partition - so in theory everything bar the most fundamental OS apps should be movable and usable without their code even realising they come from somewhere other than internal memory, surely?)