If you look at the patterns format between LOC and LOS, you will see clearly two clk pulses in case of LOC(which means sequential ATPG algorithm is beeing used) where as the only clock in LOS(bcoz launch happens on last shift, combinational algorithm being used).
In a pair of transition fault vector(v1,v2), the state reached by vector v2 is reachable from the state obtained by v1.as a result you will see the higher coverage. some of the consecutive two states generated by LOS is not reachable in fucntional mode at all.so this may lead to yield loss.