2013 workflow multiple value managed metadata

I've got a 2013 workflow that looks up a value in another list based upon the value in a managed metadata column. It was based on this discussion. And it is working if the column is restricted to one value.

If the managed metadata column allows multiple values the workflow doesn't function properly. I'm able to get the value from the column into a string which looks something like this when logged to the workflow history:

term1|guid1;term2|guid2;term3|guid3;

I have an action that finds the pipe character, but it always returns -1 -- meaning that it doesn't find a match. But I can clearly see the pipe. I have also tried various letters and numbers which are also present, but no match is ever found.

Any idea how to work with multiple value managed metadata columns in 2013 workflows?

Update: Found another tutorial​ on how to make a custom activity for the workflows. I don't have visual studio or the knowledge to make a custom activity, but I want to put it here as another clue.