When you NETFILEd your return in 2017, did you save your return after filing? If you didn't save it at that point, then then the file doesn't know that you have NEFILEd. If you have the .ttbk of that file, you can try changing the extension to .tt17 and see if that shows as NETFILEd.
You can also make changes to your return through the CRA's My Account: https://www.canada.ca/en/revenue-agency/services/e-services/e-services-individuals/account-individua...
