You shouldn't have to resample. As Jeff mentioned above, you need to make sure that when you go to save the file in AA3, on the Save As box click "Options" at the very bottom, then make sure under "Format 32 bit data as" select > "24-bit packed int (type 1, 24-bit)".
It is normal for AA3 to open your 24-bit WAVs as "32-bit integer float", but something triggered your saving options (Windows update or otherwise) and likely needs to be reset.
I, too, have been using AA3 for 10-12 years on a Win 10 machine and had no issue transferring shows last month. I also opened the edited WAVs directly in CD Wave afterwards for tracking, so the workflow was the same as yours.