1- create a gradual tempo change. mine is particularly weird above cuz i needed to make a rallentando (and yes, i had to look that up)
2- set your snap to some obvious grid value - i chose 1/4
3- move your item. NOTE- snaps to 1/4 notes as expected.
4- shift-slide your item offgrid and into the tempo change space. drop it somewhere mid-grid.
5- release shift and move your item back to A tempo.
ISSUE: the item still snaps to 1/4 grid, but not the item start. note the weird offset in the gif above.