I am not sure whether it is a problem within Karaf features or offliner but there are features that are not possible to be installed while offline using offline repository. All of these features are failing due to these few missing dependencies:

• org.atmosphere/atmosphere-runtime/2.4.16
• io.fabric8/kubernetes-model/2.0.10.fuse-760013
• io.opentracing/opentracing-api/0.31.0
• org.apache.servicemix.bundles/org.apache.servicemix.bundles.javax-el-impl/2.2.5_1
• org.apache.servicemix.specs/org.apache.servicemix.specs.javax-el-api-2.2.5/2.2.5_1
• org.fusesource.camel-sap/7.6.0.fuse-760021-redhat-00001
• org.ops4j.pax.jdbc.oracle/1.4.4
• org.ops4j.pax.jdbc.teradata/1.4.4

all of these dependencies are downloaded with different version:

• org.atmosphere/atmosphere-runtime/2.4.20
• kubernetes-model/2.0.10.fuse-760013-redhat-00001
• opentracing-api/0.31.0.redhat-00008
• org.apache.servicemix.bundles.javax-el-impl/3.0.0_1
• org.apache.servicemix.specs.javax-el-api-3.0.0/3.0.0_1
• org.fusesource.camel-sap/7.6.0.fuse-760021-redhat-00001 - not even trying to download
• org.ops4j.pax.jdbc.oracle/1.4.4 - not even trying to download
• org.ops4j.pax.jdbc.teradata/1.4.4 - not even trying to download

it seems to me like a problem with alignment more than a problem with offliner but not sure.
List of affected features:

• camel-atmosphere-websocket
• camel-kubernetes
• camel-opentracing
• camel-sap
• cxf-tracing-opentracing
• cxf-transports-websocket-server
• hibernate-validator
• hibernate-validator-paranamer
• pax-jdbc-oracle
• pax-jdbc-teradata
• pax-jms-ibmmq