Master mixer effects have no effect

Hello… everybody!

So i am attempting to insert an effect on master bus in groove agent 4.2.5.

I have one acoustic agent and one percussion agent playing. There output are both set to master.

However, the insert has no effect on the master bus.
Inserts are working fine on the kit bus.

I have consulted the manual but alas here i am.

Any ideas would be greatly appreciated

Thanks

And today it works… how strange