"ERROR: Failed to convert input file." when specifying -u

[asdfzxcvbn]

azule will inject 5/7 of my dylibs, and then fail:

[*] Injected 000RocketLoader.dylib
ERROR: Failed to convert input file.
[*] Removed UISupportedDevices from app
[*] Restored App Entitlements
[*] Generating iPA...
[*] Generated IPA at <path>
[*] Removed Watch App

when the -u option is not specified, everything runs fine.