Hi,
Visualy it’s clearer, if you use the Square tool instead of the Sine.
If I understand you correctly, you would expect, the sine length is always the same, because the Grid is set to Bars+Beats. So if the length of the Sine is 1/2, it will alwas be 1/2, independent on the tempo. But it’s not the case, it’s more time-base, so if you change the tempo, the length remains time-wise but it’s not in sync with the music anymore.
Do I undesrtand you right?