Send FX lower in volume when creating busses - any idea why?

Hi guys,

I write music for tv which requires a lot of stems bounces as clients like to work with stems to build the track around the picture. I’ve noticed that my process of bouncing them out is causing my send fx to go down in volume and wondering if you maybe have any guidance on this.

Quick explanation of how I go about mixing my groups:

What I usually do before exporting my stems is bus channels together into groups for example - drums, bassline, synths etc… I then apply mastering fx (limiting,compression and excitement) to each bus instead of the master channel and I do a mixdown like this before exporting.
This basically allows me to export each stem as loud and in your face as the “master track” so that when the client or editor pulls it into their project session the stems sound just as powerful as the track they chose.

Now here is where my issue comes, after i group everything together and mix it, I notice that all the send reverbs are a lot softer, and I have to make all the reverb sends louder. Any idea why this happens and if there’s a way to fix this?

Thank you for your time

not sure…
Maybe you have the fx returns routed to the group and to the main out?