Retrieve variables from layers?

I have a couple of courses that I use as recruitment tests where I have multiple text entry fields on a slide and am able to pass all of those text entry values to my LMS using short answer questions. I use a method similar to the one described here: https://articulate.com/support/article/Storyline-360-How-to-Send-the-Value-of-a-Variable-to-an-LMS. So I have my slide, a learner puts 4 answers in 4 fields, their answers each go into a variable for each field and then I use a short answer question to retrieve each variable and submit it and I do that for every text entry field. It works just fine.

I now need to do the same, but with the text entry fields on multiple layers of just one slide. So where I previously had, say, 4 fields on the base layer of one slide, I now have 1 field on each of the 4 slide layers and I still want all 4 variables to get passed to the LMS. (hope that makes sense!)

The course is getting stuck when it gets to the second short answer question and I can't see anything obvious wrong so before I spend a lot of time troubleshooting, can someone confirm that it's OK to use variables on layers this way?