The version of my Excel 2016 from the active Office 365 subscription is the following (from the About window):
Microsoft Excel for Office 365 MSO (16.0.11126.20234) 32-bit.
It seems, you have an outdated installation. Just in case, try to update it.
Could you use iGrid in this Excel earlier without any problems? If the problem has occurred only recently, it may be related to a Windows update or something like that.
And do you want to say that you can't even drop iGrid from the toolbox on a UserForm?
Can you reproduce this behavior on another similar pc?