[vsrs_au]

@Baertram, thanks so much for the detailed reply! Also, sorry for my late reply, I'm in timezone GMT+11 (Melbourne, Australia).

My code was as follows (and as I said, taken from your tutorial):

FooAddon = {}

FooAddon.name = "FooAddon"

{{ various function definitions of the form FooAddon.functioname(...) }}

EVENT_MANAGER:RegisterForEvent(
    FooAddon.name, EVENT_ADD_ON_LOADED, FooAddon.OnAddOnLoaded)

In those functions, the references to FooAddonIndicator (defined as a top-level control in the XML file) are all of the form:

FooAddonIndicator::functioncall(...)

I'm still not sure exactly what I did to fix the sample addon, but it works OK now. I guess I'll find out one day, when I know more about ESO UI and/or LUA.