Q_PopulateResponse not working when using embedded fields

I am trying to prepopulate a multiple select question in a survey using embedded data from the contact list. I've created a test question Q1, with 3 options. In my contact data I have a field called Q1Hist which I've added as embedded data in the survey. Values in this field are 1,2 or 1,3 for example.
Using Q_PopulateReponse I want to prepopulate Q1 with the values from Q1Hist. I'm having trouble trying to get the data from the url to populate the question responses.
If I hard code the responses in the url everything seems to work and my Q1 question responses are populated correctly, but if I reference the embedded data field Q1Hist it does not work:
Scenario 1:
&Q_PopulateResponse={"QID1":"1,2"} works
Scenario 2: 
&Q_PopulateResponse={"QID1":"${e://Field/Q1Hist}"} does not work

(note: I'm using an ampersand because I'm joining to personal links and there's already a question mark in the url. I also encoded the quotes with %22 to see if that made a difference)
I've also added a text/graphic question to pipe in the values of Q1Hist and Q_PopulateResponse to see what data is coming into the survey. In both scenarios, Q_PopulateResponse is picking up the correct data but when I used scenario 2 with the embedded data question Q1 does not populate.
I used this as a guide on the Qualtrics website: https://www.qualtrics.com/support/survey-platform/survey-module/survey-flow/standard-elements/passing-information-through-query-strings/#HowToQ_PopulateResponse
So, I'm wondering whether anyone knows if there's a trick to this, or have I missed a step in the setup somewhere?

Thanks