It seems like Synapse 4 has not yet got official support for using profiles from Synapse 3. If it’d work via sync that would be perfect, but in the meantime, exporting profiles from 3 and importing into 4 would be okay, too. As far as that goes I found out that one can select .synapse3 files on importing profiles in Synapse 4, by selecting “All files” on the bottom right of the file selection, but it seems that this doesn’t work correctly, yet. I was able to import the profiles for my keyboard (Ornata V2) as well as for my mouse (Basilisk V3), but not for the Tartarus V2 (which has by far the most profiles). Maybe that should work and it’s just a bug (if you found a fix/workaround for that, please let me know), but no matter how it is, it would be great to know, when an official support for importing Synapse 3 profiles into 4 will come (estimated).
I really, really like the experience so far with the new Synapse and I can’t wait to make the switch, but I’m not very fond of manually configuring my ~50 profiles again.