I have been doing some testing on my iphone6 and I noticed that with 493 songs it simply does not want to let me select all, then open, in order to import songs from google drive? Once I hit Done it goes off into the weeds. I found thru experimentation that I can do a "letter at a time"...i.e... did all the As, then the Bs, etc. After a couple of minutes files selection screen goes away and I see the "Importing Songs" popup window in ST3.
Also, is there a way to zero out the Songs in ST3 and start over?