Custom Column Like: In Issue Material Problem

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We're using lots within our system and I'm having problems with the Issue Materials entry screen. When you go to issue a part the Onhand qty is always showing incorrect values.

I've had a look at the Custom Data dialog and there are 3 foreign views, In The Custom Column likeL the field onhandqty field is linked with the Parttran.tranqty which doesn't seem to make much sense.

What I'm trying to do therefore is to change this likevalue field (not working) or create a BPM that updates the value of this "IM.onhandqty" field to the actual partlot.onhandqty.

Any ideas on this?