JIRA Cloud custom colour theme displays default blue instead

Summary

Custom colour schemes in JIRA Cloud are not applied but show the default blue theme instead.

Environment

• JIRA Cloud 1000.844.1

Steps to reproduce

1. Go to System > Look and Feel
2. Update the Header Background Color
3. Refresh the page

Expected result

The header colour is updated.

Actual result

The header colour remains as the default colour

Notes

The colour theme details in the "Colours" section of the "Look and feel" page are displaying with the correct custom colours, but JIRA is displaying all the default blue colours for the header, link, and so on.

Workaround

None yet.