Exactly.  However, this is completely lost on TurboTax.

For the error on the T3 slip not balancing box 52+53 to equal box 21A, trying to enter the sum of 52+53 into box 53 (deleting 52) should fix the problem.

We are aware of this issue, and our development team is working on a resolution. We appreciate your patience.

Thank you for choosing TurboTax.

I am experiencing the same issue.  It is not pulling the data from box 21 to form 936.  I do have boxes 52 and 53 completed on the T-slip, but the field on form 936 is zero.  As a result I am not able to submit the return using Netfile.  ETA on getting this resolved??

@CM1965 . Currently we don't have any ETA. Once it is resolved, we will update you in this thread. We appreciate your patience.

Thanks so much that worked for me as well