PENDING ConfigMgr bgbisapi.msi could not be installed write access

[KAdabra]

Hello,

Afer upgrading to 1806, i a m experiencing bgbisapi.msi reinstallation issue on two primaries.
Trying to follow the procedure https://prajwaldesai.com/fatal-msi-error-bgbisapi-msi-could-not-be-installed/ BUT:
only trustedinstaller is allowed to modify installutil.exe.config , preventing me from adding <runtime> specification.

Any guess ?

Thanks in advance