Please make sure you are familiar with repeatable sections before continuing.
When merging a repeatable field with a question label that contains a token from a repeatable section (either the same or a previous repeatable section), you must convert each reference code into the composite reference that identifies the instance of the repeatable field to be merged. As outlined here, you can convert a field's reference code into a "composite reference" by adding a tilde (~) and an instance number (e.g. 1, 2, 3...) after the last digit of a reference.
In the example below, a token is used (white text with blue background) to insert the answer to the field Applicant #Repeat - Full Name: into the question label of the fields that follow.
Here, the second field's () label is [@100430073]'s contact number: - "[@100430073]" is a token for the field Applicant #Repeat - Full Name:.
In order to merge a label that contains a field reference - such as [@100430073]'s contact number: - you must convert the field reference into a composite reference by adding "~n" where n is the instance number e.g. "~1" to merge instance the 1st number. In the example above, the label to merge the 1st instance of [@100430073]'s contact number:. is [@100430073~1]'s contact number:.
See the image below for some more examples of how composite field references should look to be correctly merged.