I spent 1 hour with Turbotax tech support yesterday. Have you been able to solve this issue? This is preventing me from submitting my Provincial document.
If you completed part 3 of TP-59-S-V then you do indeed need to fill out TP-64.3 as it was provided to you by your employer.
The issue (described in this post: https://turbotax.community.intuit.ca/community/troubleshooting/discussion/error-on-quebec-form-when-...) arises if you only completed part 1 and 2 of TP-59-S-V in which case you DON'T need the TP-64.3.
You can find TP-64.3 by searching the forms in TurboTax but you need to have it completed by your employer for you.
Did you find a solution for this? I am also running into the same issue, this seems to be related to the fact that I received a T2200s from my employer but Turbotax doesn't seem to be sending the proper form with my NetFile. I called support and was told it was a known issue and they would fix it soon, but it's been over a week already and I'm getting annoyed since I was already able to NetFile with the CRA and I wanna get this done asap as well.
Are you using the Onlive version? I ended up using the downloaded version and it worked. I was able to submit my Provincial return. If you paid for the online version, call support, and they will reimburse you for the downloaded version.
I don't know if the issue on the Online version has been resolved.