Just FYI: upgraded from host V0.95 F (GRR) to V1.6.0. In V0.95 a G28 X Y or G28 Y X would home both axis, in V1.6.0 only the first axis is homed, a G28 X0 is sent to the printer. G28 x0 y0 does home both axis.
You must have a number after each parameter name. Omitting it makes you rely on automatic error detection.