There are no errors in the developer tools console, on either form. I am pretty certain that the configurations are correct, and every other aspect of vLookup is working properly. It is just not pulling any information into the child item for the other list.
There is a third location in the site collection where vLookup is being used, and this one seems to be pulling information from the parent list into the child list form, as expected. The settings all look the same across the board–just doesn’t seem to be working in the other two locations. Heard anything like this before?
Thanks