Have you tried checking the registry key at HKEY_CURRENT_USER\Software\Microsoft\Office\Excel\AddIns\PI DataLink. ?
The LoadBehavior DWORD should be set to 3.
Also check the registry for the Local Machine as well as current user.
I am also curious, was the add-in visible before? If yes, did you do anything before it disappeared?
Thank you for your response. I did check the registry key for Local Machine and the LoadBehavior is set as 3. But I couldn't navigate to Excel\AddIns\PI DataLink through HKEY_CURRENT_USER because, under office\excel, I do not see AddIns folder but only the Add-in Manager folder and no Datalink under this.
The COM Add-in for PI Datalink was available earlier and I was using the same last week. As it is in a shared machine, I assume some other user might have removed it by mistake. As mentioned in the KB00265, If the add-in is manually removed, I may need to re-install the PI Datalink to bring the add-in back. Please suggest if there is any other option.
Request you to check the post Problems to Display the Datalink Tab in Office 2016 32x . We have installed datalink on office 2010 ,2013 and 2016. I have noticed issue with office 365 due to patch updates or excel crash where add-in is not loading correctly. I have tried all possible options mentioned in my post and able to solve most of the problems related to Datalink missing add-in.