Has anyone flown a spark at 12000 feet above sea level. I’m thinking of taking mine to La Paz Bolivia and want to know if it will fly.

It will fly. You may notice a reduced flight time though.

Cheers,
Wolferl

I think, I have seen ...., found it:

Hello and good day. Thank you for reaching out and for sharing these information. The DJI Spark can be operated properly on these conditions. The Operating Temperature Range is from 32° to 104° F ( 0° to 40° C ) and the Max Service Ceiling Above Sea Level is at 13,123 feet ( 4,000 m ). Have a safe and happy flying always.

I have taken my to about 8000' feet (from normally about 1000' operation) and have noticed that it stops a lot slower when going really fast in  sport mode.
I crashed mine into a tree haha (no damage).