Hey Bassem,
Thanks for the detailed note. Your client’s STP reports getting rejected while yours as the tax agent are accepted does often point to the client’s Software ID setup. The best step is to check the exact error code shown and then follow this Help Article for the fix. If it’s about Software ID, look for the SBR.GEN.AUTH.008 section and have them re‑register/confirm their ID in ATO Access Manager or call the ATO. If the error you're seeing isn't listed on the article, make sure to reach out to our team on Live Chat via our virtual assistant, MOCA, or by submitting a support case via MyAccount. They'll be able to provide the workaround based on the error code received.
Cheers,
Doreen