Time Log "not invoiced" amount decreased with no invoicing activity

On Echo's account, the Time Log report's not-invoiced total for Maestro Den dropped from $659.00 (Echo's printout) to $630.34. New time can raise this number, but nothing Echo did should lower it.

Expected: the not-invoiced total only goes down when time is invoiced or marked billed. Find what changed the $28.66 and confirm the correct figure is $659.00 plus any new time logged since.

Related to: "Ready to Invoice unbilled time doesn't match Time Log report"