Source sprint value is not syncing with target custom field in Jira Datacenter v10.3.5

In Jira Datacenter v10.3.5, we are trying to copy the sprint value from source to a custom text field in target. Below is the script we are using:

Soource:
replica.sprint = issue.sprint

replica.customFields.“Sprint” = issue.customFields.“Sprint”

Target:
issue.customFields.“CR ID”.value = replica.customFields.“Sprint”.value[0].name

The source is sending the payload but the target is blank.
Any suggestions on how to make this work?