I ran into a similar situation. After I right clicked the TT program icon to change the compatibility mode to XP SP2, the next time I started TT it made me re-enter the activation code. I don’t know how many installs I am allowed, but that it must be at least two uses of the code. Also, your PC probably needs Internet access long enough to verify the activation code. If you are out of allowed installs for your activation code, it seems like phone support from customer service is likely the only option remaining.
TT 2019 has certainly become a bug-fest, at least for running on Windows 7. They have it backwards - the program should run more smoothly with updates, not worse.
