When trying to get flint i gather gravel and stacked it and then at the bottom i mined a gravel block and swiftly i placed a torch underneath and i was expecting to get gravel blocks and flint instead all the gravel started disappearing and i received nothing.
This bug also happens in Creative Mode.
The only way to get flint is by using a shovel not through drop conversion with a torch but I concur that the block sand/gravel blocks are indeed destroyed instead of converting to drop blocks like the PC version of MC.
Confirmed in Survival on Android Desire HD & Nexus 7.