Hi again,
I forgot that YITH had changed their code.
So the solution of Sam Aka is the still the best:
ok everyone, looks like they have changed their code again. so this is how we work around it in the last versions as of July 2019 versions:
inside the Yith plugin root folder go to:
plugin-upgrade>lib
there you should edit the file yit-license.php as following:
before line 837 (add /**)
after line 857 (add **/)
