Solved: Custom fields not visible after upgrade (2.3.4 -> 3.2.1)

-- HikaShop version -- : 3.2.1
-- Joomla version -- : 3.8.3
-- PHP version -- : 5.6.1
-- Browser(s) name and version -- : all
-- Error-message(debug-mod must be tuned on) -- : none

Custom fields were not showing in front or back end after upgrade from 2.3.4 -> 3.2.1. Simply (re)saving each custom field fixed the issue. Just fyi...