Molding Without Seizing
I've tried the molding method you mention (10-15 minutes in the freezer), but when I take them out of the freezer, the change in temperature causes a sheen of water to form all around the outside of the chocolate, seizing the shell (YUCK).
I've tried using paper towels for the chocolates to rest in while returning to room temperature, but it didn't work well.
I also tried leaving the chocolates in the mold at room temperature, but that takes forever to set - and actually turned out too soft for some reason.
Several people have been having difficulty lately molding without seizing their chocolate.
I actually probably wouldn't call it seizing, but more a case of condensation building up on the chocolate as a result of the change in temperature when returning to room temperature.
Seizing is when you get water or moisture in the chocolate while melting it. The chocolate seizes up and becomes nearly impossible to work with, even though it still tastes okay.
Here's an idea to try...
When you remove the molds from the freezer, immediately tip them out onto a clean dish towel (not paper towel) and cover them with another one.
This should allow the chocolate to adjust to the change in temperature more gradually and reduce the condensation or sweating of the chocolate.
Let me know if this makes a difference for you. Meanwhile, I'll see if I can find any other recommendations for you to try.