Surface mount ceramic capacitors are prone to cracking once they are soldered down. When the board flexes, it causes the rigid ceramic to flex, generating an internal crack.
This is an issue on "stiff" PCBs, so you can imagine it is also an issue on flexible circuit "board" material.
Make sure you use ceramic capacitors that have a "flexterm", "flexible termination", or "polyterm" (different manufacturers call it different things). Its an epoxy added to the terminations to allow the solder joint to flex, without transmitting the mechanical strain to the ceramic body.
Distributors like Mouser generally let you select these as a search filter.