rests don't snap to grid?

Since my initial post about this, I've encountered another problem with rests that might be related. I first assumed it to be specific to one score and therefore explained by some odd corruption, but now I think I can describe the issue and the context - so here goes:

I'm unable to drag any rests when in Page View and in any measure beyond the first page of the score. In these circumstances, the rest can be dragged in some small increment - but it really doesn't work at all. The direction and the amount of that small increment seems to be erratic.

In Continuous View, however, click-and-drag of rests seems to function correctly regardless of location in the score - but subject to the limitation I initially described (i.e., the rest can be repositioned at will in any direction by clicking and dragging ... but snap-to-grid remains unavailable).

Wow ... now something else, FWIW. All of the above refers to rests that are *not* whole-measure rests - but I've just now also noticed randomly weird and unpredictably jumpy click-and-drag behavior unique to whole-measure rests that happens anywhere in the score and in either Page View or Continuous View. (Of course, there would never be an actual need to reposition a whole-measure rest in this manner - but that's not the point, which is why I included 'FWIW'.)

The attached score is derived from the Piano Solo template, and I've used it to play around with what's described here.