The UnityExplorer.Standalone.Mono.dll needs to be in the Dependencies/ subfolder to load correctly, but the build automation currently places it in the same folder as the Distance.UnityExplorer.dll mod.
Releases where the UnityExplorer dll is included, but placed in the same folder as the mod dll
Possible leads
Release Workflow-Automated Deployment [#4] is the only one to have the correct Dependencies subfolder structure, so it may be useful in figuring out what's different about the build targets and automation.