@rpiMike - Yes the 8 flashes is a comm problem on i2c.
The first question we always have to ask is do you have a good power supply?
Next, can you try changing the PI CPU scaling governor from ondemand to performance to see if that makes a difference? Details here:
https://community.zymbit.com/t/dev-team-known-issues/996/3
And one more question on your setup: How is your MCP3008 wired up? Is it on a standard HAT, or are you wiring up yourself on a breadboard?
Bob