Hi Benjith,
Thanks for your reply! I will mark your answer as the solution since this solves my problem. I also came up with an alternative myself by changing the last assign in the flow:
If(Index(String_Join.Text, ";") = 0, Substr(String_Join.Text, 1, Length(String_Join.Text) - 1), String_Join.Text)
This also solves the problem, but it in my opinion your solution is better, because you solve the problem in the beginning and not at the end.
Best,
Bart