I noticed that the deployer credentials stored as global variables cannot be substituted when promoting a release (Artifactory Release & Promotion tab).
When running an Artifactory task-based plan (snapshot build) or staging a release from the release management tab, the credentials stored as global variables can be substituted but not by promoting.
Using Bamboo 5.5.1 and the latest snapshot version 1.7.3-SNAPSHOT offered by Eyal Ben Moshe in
On the promotion tab I got:
Replacing the variables with username/password in plain text works.