A hotfix has removed the ability to transfer Dragon Isle Supplies amongst your Warband.
In a hotfix a few minutes ago, Dragon Isles Supplies are no longer able to be transferred across your Warband — there is no option to open the currency transfer window anymore.
We have absolutely no idea why this change happened considering an article previewing Warbands showed an image that specifically Dragon Isles Supplies could be transferred. Was there some exploit that was occurring for them to disable this?
Blizzard has confirmed that they have disabled currency transfers while they work on a solution for a problem with them, but they should be re-enabled once the issue is addressed.