I just had the same syncrosoft problem with SX3.
Thanks for the solution, but I think this SX3 workaround for importing older projects is really annoying and unacceptable!
I recently had the same error message and I upgraded to the newest LCC but I still get the error message upon opening SX. I also don’t see an SX registration on my e-licenser but I honestly can’t remember if one is needed as I haven’t used SX for converting for a number of months. All of my other Steiny apps (6.5, WL, Halion) open and operate just fine.