Make sure that the INF dataset/member specified in the REPRO command already exists.
A new Dynamic PDS member, when used as INF in a REPRO command, becomes unsuitable if it has not been updated before the REPRO command processing. In the case of dynamic PDS members, a reference to a non-existing member in the JCL leads to the creation of an empty member, and at the end of the job step, it will be deleted if it has not been opened for output/extend/update.