This might be relevant? S7 1500 Tags Writing Issue - #17 by Kevin.Herron
I don't remember what I found out when I looked into giving an error or something for this issue. If you share more details, I can take a closer look sometime.
Debug logs, wireshark, TIA project, repro steps, etc. You can upload here:
Edit: To be clear, it is expected not to be able to write to inputs. The "issue" is that the driver doesn't give an indication of this. I'm not sure if it can or not. It's possible the PLC "accepts" the write and does not provide an error.