I'm using the desktop version of Turbotax and have the same problem. Gave up trying to make T5008 work and manually entered all cost base/proceeds in Section 2 of Schedule 3. This does not give you the ability to specify if the sales were period 1 or 2, Turbo Tax seems to make its own decision to put this in Period 2. Guess it doesn't matter if the inclusion rate is 50% for either Period.
What is equally frustrating for me is that some of the T3 slips generated by mutual fund companies list the split (Boxes 52/53) while others report only the total in Box 21. TurboTax refuses to acknowledge Box 21 anymore leaving the user to re-enter the value in Box 52 and/or 53.
