Hello,
I hope you are well.
The IE Plugin can only be used with the MTS versions of Mendix Studio Pro, specifically version 10.6.11. Therefore, I recommend using this version, as it is the one we currently support.
Please note: Version 10.12.2 is also an MTS version. However, the IE Plugin is not functioning with this version at the moment. We are working on releasing a compatible version of the IE Plugin for version 10.12.2 soon.
Best regards,
Rafael Curiel.