Currently using an HTC Desire 510 with Android 4.4.3 It has a total of roughly 3.8 GB interal storage (not counting application storage). But about 3GB are occupied by what the phone considers "Other files", not letting me see which files those are.
When I connected to a PC through USB I did find a file named ".thumbdata" in DCIM/.thumbnails weighting over 2GB, which I immediately deleted. The empty space in my phone remained unchanged, so I restarted it a couple of times. The file reappeared, now weighting just 30MB, but the source of those used up 2GB is nowhere to be found. What can I do?