Wait, they're falling apart just this shift? That's wild if your mix hasn't changed at all. You gotta check if the sand bin got contaminated or something, maybe someone bumped the water line.
Ugh, that's the worst feeling when your molds just fall apart. To really help, we need to know what's changed. What's your current mix ratio for clay and moisture, and are you using any additives? Also, how's the compaction been this shift compared to normal? Sometimes it's not the mix, but how it's being packed.