So, if I understand correctly, you've lost configuration of the field after upgrade, correct? That shouldn't happen unless upgrading between major versions. What was your previous version?
If this happened, unfortunately, the settings can only be accessed programmatically from the field's schema.
Cross-site Lookup schema is similar to the out-of-the-box lookup but contains additional attributes. Here's an example:
Code: Select all
<?xml version="1.0" encoding="utf-8"?>
<Field
Type="Lookup"
Name="Country"
DisplayName="Country"
JSLink="~sitecollection/style library/plumsail/crosssitelookup/clienttemplates.js?field=Country"
xmlns:csl="Plumsail.CrossSiteLookup"
Mult="FALSE"
csl:ShowNew="false"
csl:RetrieveItemsUrlTemplate="function (term, page) {
 if (!term || term.length == 0) {
 return "{WebUrl}/_api/web/lists('{ListId}')/items?$select=Id,{LookupField}&$orderby=Created desc&$top=10";
 }
 return "{WebUrl}/_api/web/lists('{ListId}')/items?$select=Id,{LookupField}&$orderby={LookupField}&$filter=startswith({LookupField}, '" + encodeURIComponent(term) + "')&$top=10";
}"
csl:ItemFormatResultTemplate="function(item) {
 return '<span class="csl-option">' + item["{LookupField}"] + '</span>'
}"
ID="{93c08653-b2e1-4342-b04f-8f32596b6633}"
SourceID="{fce5ae43-52aa-4f03-aa93-667112e7b5ce}"
StaticName="Country"
ColName="int1"
RowOrdinal="0"
Version="2"
WebId="{78a5e7dd-b782-4b2d-bf9a-893b5193d4ab}"
List="{275da0fb-d2cc-42c6-b82a-ed16ca87ea98}"
ShowField="Title"
csl:NewText="Add new item"
csl:NewContentType="" />