Cannot deploy garrisons

I'm trying to deploy some garrisons to a country I have, mostly for purposes of upgrades, but they're refusing to deploy. I built the blueprint, and then I go through the Deploy Garrisons screen, set the appropriate number of targets to have garrisons at 100% strength, and hit Deploy. I can even set their quality levels to upgrade. But there's no forces there, and the levels aren't going up, just units sitting in my stockpile.

What on earth is happening?

Do you have supply units?

Had only a short time to post before. Anyway, unlike other units, garrison units are not deployed to the map instantly. You set a blueprint for what you want and where you want it and your deployed supply units will gradually deliver the requested weapons and ammo to the selected locations. Removing garrisons likewise is a process of supply units picking up weapons and ammo and returning them to your stock. For the most part, the purpose of supply units is to maintain your garrisons.

I have one small supply unit, and tried to put down 30 full garrisons. I'd expect it to go slowly, but it seems like zero actual deploying has gotten done, and I waited a couple RL days before posting this thread.

Addendum: Added a bunch of large supply units, stuff's starting to deploy now. Not terribly fast, but it exists. Problem solved.