$lookup not being performed for an item in GPCCMP form

[liambarnes]

Describe the bug
When a Questionnaire is being prepopulated with a coding that does not have a display, a $lookup operation is requested of the terminology server and added to the QuestionnaireResponse. This is not always happening.

To Reproduce

1. Open GP Chronic Condition Management Plan in Playground
2. Prepopulate with patient = "foreman-caterina"
3. Go to "Clinical details" tab, "Medications (current)" section and observe the 3rd "Recorded medication" populated has a "Medication" = 682641000168107. This is the SNOMED CT code from the coding in the MedicationStatement resource used to prepopulate. Performing $lookup should have retrieved the display for this code and correctly displayed it. Interestingly, the "Indication" item is being populated using a coding from the same resource that also does not have a display, yet a $lookup request is being made for this item and correctly retrieving the display.

Expected behavior
Described in reproduction steps.