Steps to reproduce:

• Create an issue in JIRA and estimate 2 hours of work
• Perform a search in JIRA for this issue and save it on a filter
• Create a Confluence page and add the Filter Results macro to it
• Configure this gadget to use the filter saved in the second step. Also, add the following to Fields to display: Σ Time Spent, Σ Remaining Estimate, Σ Original Estimate and Σ Progress.
• Since you haven't logged any work on the issue, the Σ Progress will be displayed as 0%
• Now, log 1h of work on the issue.
• Refresh the Confluence page, the Σ Progress will be displayed as 50% and the progress bar next to it will be half Green and half Orange (Green means Done and Orange means ToDo)
• Now, log 3 hours on the issue (or any value bigger than what was originally estimated)
• Refresh the Confluence page. The Σ Progress will be displayed as 100% but the progress bar will be empty, like no work has been done on the issue.

As a side note, if you display the Σ Progress in JIRA's issue navigator, the progress bar shows correctly.