KSP-AVC not detecting a new version

[geoffromer]

I just discovered that I've been running a stale version of kOS for quite some time, despite having KSP-AVC installed. The KSP-AVC interface lists my version of kOS as 0.15.4, which matches my kOS.version file, but 0.15.5 seems to have been the latest version for some time now. I see the following in my KSP.log:

LOG 15:58:44.195] KSP-AVC -> /Users/gromer/Library/Application Support/Steam/SteamApps/common/Kerbal Space Program/GameData/kOS/kOS.version
NAME: kOS
URL: https://raw.githubusercontent.com/KSP-KOS/KOS/master/Resources/GameData/kOS/kOS.version
DOWNLOAD: TODO - when release...
GITHUB: KSP-KOS/KOS
LatestRelease: NULL
AllowPreRelease: False
VERSION: 0.15.4
KSP_VERSION: 0.90
KSP_VERSION_MIN: 0.90
KSP_VERSION_MAX: 0.90.99
CompatibleKspVersion: True
CompatibleKspVersionMin: True
CompatibleKspVersionMax: True
CompatibleGitHubVersion: True
[LOG 15:58:44.195] KSP-AVC -> https://raw.githubusercontent.com/KSP-KOS/KOS/master/Resources/GameData/kOS/kOS.version
NAME: kOS
URL: https://raw.githubusercontent.com/KSP-KOS/KOS/master/Resources/GameData/kOS/kOS.version
DOWNLOAD: TODO - when release...
GITHUB: KSP-KOS/KOS
LatestRelease: 12.1
AllowPreRelease: False
VERSION: 0.15.5
KSP_VERSION: 0.90
KSP_VERSION_MIN: 0.90
KSP_VERSION_MAX: 0.90.99
CompatibleKspVersion: True
CompatibleKspVersionMin: True
CompatibleKspVersionMax: True
CompatibleGitHubVersion: False
UpdateAvailable: False
[LOG 15:58:44.195] KSP-AVC -> Identical remote version found: Using remote version information only.

The remote version sure doesn't look identical to me...