Answer question
IM 4.1 - installation of rollup 1 may cause the Preview toggle button on the Plant Explorer to be grayed out
Problem:
re-registering the AfwAbsInterfaces.dll corrected the situation
1. open a Command Prompt
2. regsvr32 'C:Program FilesABB Industrial ITOperate ITProcess Portal AinAfwAbsInterfaces.dll'
Symptoms:- Article imported from the previous version of KnowledgeBank