When I arrived home tonight I downloaded the latest version of TQSL and updated the configuration file per the instructions. I deleted the conversion from FT8 to data filter that I had put into place a few weeks back.
Then I exported all my FT8 contacts from my logging program in ADIF format.
I opened TQSL and signed this new export file and uploaded it to LoTW as usual.
Ten minutes later, the 500 contacts that I had made using FT8 but had uploaded as a DATA type magically turned into valid FT8 contacts, exactly the way the instructions said it would work.
I love it when a plan comes together.