Hey! We can't seem to produce the bug with the simplified skeleton you sent.
By removing the other attachments, you may have removed the bug case. It also looks like the pies already have the 2% assigned.
It's hard to tell what caused it here.
Also, has your team tried updating to 3.6.52? The bug might have already been previously fixed.
The jump from 3.6.38 to 3.6.52 shouldn't cause any compatibility problems. Of course, as usual, keep backups of your files.
If this did not fix the problem and is causing you problems, do let us know!