Full diamond armor, boots with depth strider, helmet with aqua-affinity. Waded into shallow water, dug some clay, was unable to surface; the up/down controls stopped responding, struggled to surface for a long time, avatar died.

It appears that the depth controls are not getting serviced by the program when this happens. Other controls are working (forward/back/left/right) and touch screen still responds outside of the frozen control buttons. May be related to the bug with minecarts.