Very strange behaviour with side chaining

I was in a session earlier today where i had a compressor across the main outs with a s/c controlled by the kick to duck the entire track to give it a bit of pump… i also had compressors across my main guitar buss, keys buss and strings buss but triggered by the main vocal to help the vocal sit in the mix a bit better…
I then put the steinberg vintage comp on an insert on the cymbals bus i had rendered from BFD2 and then all kinds of crazy stuff started to happen!
I wanted to assign a lead guitar part to the ‘ducking busses’ but when i tried to assign from the ‘sends’ section of the channel edit window one of the comp busses had been reassigned to the vintage comp which did NOT have the S/C option active!!
i do not know if this is a known bug but it’s SERIOUSLY messed up!!! also i could not assign a compressor to an aux return which would show up as an assignable s/c either… strange again!!!

I’m using 6.0.2 rather then 6.0.4 because some of the problems some people seem to be having.

Can anyone recreate?

I’m also running several UAD plugins at the same time.

Cheers for any input!

oooookkkkk… another day and more strangeness!
Just tried to reproduce and couldn’t!
Still can’t get s/c active on the FX return channel though…