bossbar does not display when created in a load tagged function

I have a function that's tagged as load. It runs the following bossbar commands:

bossbar create allthings:progress "All the Things"
bossbar set allthings:progress max 636
bossbar set allthings:progress color green
bossbar set allthings:progress visible true
bossbar set allthings:progress players @a

However, when I reload the world, I need to re-add my player for the bossbar to appear. I've tried this with @p as well as @a in the set players command. As well, I've toyed with the ordering of the bossbar commands in the load function.