Diff from a step execution is unavailable after step finishes

Created by: courier-new

Steps to reproduce:

Kick off server-side execution for at least one workspace without a cache result
Open workspace details for that workspace
Wait for step to begin execution
Click "Diff" tab for the step
Observe "Diff not available" message
Wait for step to finish execution

Expected behavior:

Actual behavior:

"Diff not available" message persists
I have to close the workspace details, re-open it, and click back into that step's "Diff" tab for the diff to be visible

Recording of reproduction steps: