I don't have any crash logs to show but I did a quick test as I was having issues with my game on mobile. I found out that if I tried String Concat (with 4 args) that it would either get ignored (iOS) or crash (Android). Maybe test on your end to see if you get the same issue.
I got around the issue by using Concat w/ 3 args and then Concat w/ 2 args and it works fine.
Customer support service by UserEcho