Cannot display more than 100 comments on attachment

Summary

Cannot display more than 100 comments on attachment.

Environment

Confluence 5.9.9
PostgreSQL database

Steps to Reproduce

1. Add 101 comments to an attachment
2. Close the attachment preview
3. Preview the attachment again

Expected Results

101 comments would show

Actual Results

Only 100 comments are shown no matter how many more are entered

Notes

This query reveals that the comments are being stored in the database, but not displayed:

select * from CONTENT c1
join CONTENT c2 on c1.CONTENTID = c2.PAGEID
join CONTENTPROPERTIES cp on c2.CONTENTID = cp.CONTENTID
where cp.PROPERTYNAME = 'status'
and c1.CONTENTID = <content ID of attachment>;

In the query, replace <content ID of attachment> with the ID for the affected attachment. To get the ID:

1. preview the attachment by clicking on it on the page
2. copy the second number after "preview=/" for example, 557061 in this URL: preview=/98307/557061/1/557081/test.xlsx

Workaround

There is no workaround.