zplug: Most zplug commands don't work properly in a script

I’m trying to setup zplug in a bootstrap script. But after I clone it and source it, when the script gets to zplug update --self I keep getting a __job_control:set:4: can’t change option: monitor error.

If I run zplug update --self manually (in Terminal) it works. I’m guessing this has something to do with interactive vs non-interactive shell, but obviously the point of a bootstrap script is the latter…

What can I do?