Standard DTP loads, where the source InfoProvider is offloaded ADSO, are currently not supported by OutBoard DataTiering on BW/4HANA systems.
It is possible to transfer already offloaded data on BW/4HANA systems by replacing the original DTP with a DTP from CompositeProvider that consists of the BAdI provider and the original ADSO:
Create CompositeProvider and add the original ADSO into it.
Execute /wiki/spaces/OFO/pages/747536413 for this ADSO.
Create a BAdI provider and /wiki/spaces/OFO/pages/747274276 the CompositeProvider.
Create a new transformation and DTP where a source is the CompositeProvider.
Replace the original DTP in the data flows with the newly created DTP.