Negative item quantity

Good afternoon

I found a post with the same problem, but it is no longer able to be commented on. I think this might be one that requires a script from MYOB side, hopefully the right person will see this. I can't find an actual email address or messaging option on the help page. 

MYOB has crashed on me several times today, each time while attempting to enter the same bill. When I further investigated the items on the order, I saw that one had an odd negative amount (see screenshot). I attempted to adjust the quantity but was unable to change it to 0. I cleared the MYOB cache and restarted but no change. 

Please advise the best way to fix this issue.

Thanks

Karen