This URL is from
https://fundpaneldemo--release813.cs94.my.salesforce.com/a0D0R000001ih7JUAQ
Click on a Preview Body URL and you will see not all fields are merged for this preview.
https://{!aduro__Fund_Communication__c.aduro__Portal_URL_For_Template_Merge__c}/Org?org={!Organization.Id}&lp=001f400000UDWspAAH&ft=fundraising
Preview Body (URL)
(https://fundpaneldemo--release813--aduro.cs94.visual.force.com/apex/PreviewMergedBody?recordid4=a0Ef4000001aSKv&attachid=00P0R000003S1V6UAK&recordid1=003f400000jXEn9&recordid2=001f400000UDWsp&recordid3=a0Ef4000001aSKvEAM)