PCIe IP target->host MRd but no completion

Sounds like a bug that Altera needs to fix. If you can receive requests and send completions, then overall the core is setup correctly. Figures 5-40 and 5-41 show received completions with rx_req behaving correctly, so clearly the megafunction and user guides do not match. Hopefully, for now, you can design your logic to detect the completion and data without use of the req. Do the dfr and dv nets work correctly? You could attempt to alter the receive performance settings, or maybe switch to a legacy interface if possible, but I am very skeptical that these would fix anything.