How do I upload icons to Insight?

[James Sykes]

I'm trying to upload some new icons into Insight (#insight).  I have followed the documentation; accessing the icons tab within Insight configuration.  

I can select the file (.png 92 x 92 pixels) and it appears in the preview window.  However when i click update it's not processed.  See screenshot attached.

I have no idea why it won't upload.

I have uploaded new icons to service requests in JIRA Service Desk with no problems.