You need to edit the item in objectbuilder and in properties check field "market", put the name and IDs of the item in proper fields (two first fields from top, both same IDs), save changes, then edit the item in item editor by putting the same ID in one of the fields, "ware ID" I bet. And thats it.
I cannot run those programs at the moment, so I hope my instructions would be enough for you
If you'd still have troubles with it, just send me screenshots of those item in both apps.
@edit
Im on the phone... but found some screenshots of those apps. I marked the fields with blue, ignore all the rest please ^^
View attachment 52992
View attachment 52993