Ok, tried it again today, slowed down before and it intercepted nicely, started the descent, then carried on nicely and put me in a position to land about 1 mile short of the runway, in trees!
I disconnected the AP, threw the throttles to the wall and climbed out, went round and managed a manual landing but what is going on with this airport (Stanstead) and ILS??
I’ll try once more tomorrow if i can, and do a nice long straight-in approach and ILS landing, see what happens.
No custom add-on was used for the airport, just the WT CJ4, I’m using custom/standard weather and pressure was set to std.