I think there are some points to check, but I can only share what I know.
Try to change "TdmaRR" scheduler to the other (TdmaPF, OfdmaRR or OfdmaPF),
and check the log in \model\nr-mac-scheduler-ns3.cc.
If this log shows all UE's RNTI(and tbs are non-zero value), packets to transmit are correctly generated. So it may be the problem of receiving process.
On the other hand, it may be the problem of routing, packet generation or MAC scheduling if the log is incorrect.
NrMacSchedulerNs3::DoScheduleDlData()
NS_LOG_DEBUG(" UE" << dci->m_rnti << " gets DL symbols "
<< static_cast<uint32_t>(dci->m_symStart) << "-"
<< static_cast<uint32_t>(dci->m_symStart + dci->m_numSym) << " tbs "
<< dci->m_tbSize << " mcs " << static_cast<uint32_t>(dci->m_mcs)
<< " harqId " << static_cast<uint32_t>(id) << " rv "
<< static_cast<uint32_t>(dci->m_rv));