Drone build promote error: reference is not a tree

+ git fetch origin +refs/heads/release:
From https://github.com/Eerovil/myrepo
 * branch                epic/release -> FETCH_HEAD
 * [new branch]          epic/release -> origin/release
+ git checkout 984bee53a9af1a4be3c6407d33ebb3ca45acfc8a -b release
fatal: reference is not a tree: 984bee53a9af1a4be3c6407d33ebb3ca45acfc8a

Any idea what might be causing this? The commit 984bee5 is my latest commit to the PR.