It seems everyone has a different "solution" to the problem. SMC reset, PRAM reset, cleaning, language, folder workflow. Which means:
there is no clear solution!
So just to help (or not) even more, I'll add what worked for me:
- Cleaned up really good my trackpad
- Did a SMC reset
- Did a PRAM reset
None of this helped. Then this final step is what it *fixed* (at least for the time being) the problem (btw you need a mouse to make this work):
- Go to system preferences > accesibility > mouse & trackpad > then check "Ignore built-in trackpac [...]"
Play around for a bit with your mouse, say 15 seconds, then come back and uncheck that box.
THAT solved the issue for me. Again, for the time being.
Why, how, what .... who knows!?