Merging cells breaks table borders

[Peter Huson]

Sometimes, merging cells near the bottom of a tables will break the boundaries of the table. Why is this happening? Here is a screenshot: 

Confluence 7.9.1

[Brant Schroeder]

@Peter Huson Can you please share what you would expect to see and the steps to recreate the issue?  I can then try and recreate the issue and see what might be happening.

[Benjamin Horst]

In Jira DC 9.12 at least this is easily reproducable

• Create a table in visual mode
• Save description
• Merge any cells in any direction
• Save description
• Broken table

When heading to the text view one can see that some pipes are missing.