i have a comp (X) containing an animated shape layer
this composition is them dropped into another composition (Y) and had time remapping turned on
at frame 0 in comp Y, the time remapped value is set to 1
i then step through comp Y to frame 16 on the time remapped layer
set a keyframe on the remapped time
then i step forward 1 frame and the time remapped value goes from 16 to 18
if i set 17 manually, it displays frame 16
both comp X and Y have the same frame rates
That doesn't sound right. What version of AE are you using (down to the last decimal)?
What is the frame rate of the footage and your comps?
everything is 25fps