I am using Studio 2017 SR1, which should be current. Or do you mean that I should uninstall the previous version? (Usually it is possible to run both versions on the same machine, and I'd rather not uninstall the old one just yet...)

Thanks for taking the time to reply. Unfortunately, this doesn't seem to be the case. When I go ahead and create the TM, fragment alignment is disabled and cannot be enabled (it's greyed out) in the TM settings -- see screenshot below. (I also don't get the option to upgrade it in Performance and Tuning)

...so I'm quite lost...

Ohh maybe I've discovered the answer, in the "Related" links below. The checkbox is gone AND the TM will be automatically enabled once it reaches 1000 TUs (or some other sufficient number). Now that explains why I can't manually enable it in the Settings. (So your answer was correct after all Paul, thank you again -- it was just missing one detail and so I got confused...)

I have to say, it's really hard to search the forums. I had done several searches before posting, and hadn't found the answers that appeared now in the Related links :(

Anyway -- this is now solved! I have tested it by importing TUs into the new TM, and now the option in Settings is enabled. I am a happy camper again :)