It's not what the DAW looks like, it's what it does that matters. I've heard a lot of good things about RealBand.

I'm going to make sure Biab 2024 is properly updated. If that doesn't help
I'm going to try uninstalling and then re-installing Biab 2024, and all the packs again. (I know, I'm probably pissing against the wind)
If the problem persists,
I'll be rolling back to Biab 2022. I never had any problems with stems while using 2022. Hopefully, it will only be a temporary move, maybe until I've upgraded my system at some point.
I'll lose out on a lot of good stuff with 2024, but at least with Biab 2022, I could happily complete a song. I thought the problem was only with a few kits but it seems to be with every kit I choose. I'm lucky to get a kick drum here and there.
I'm also guessing the problem is somewhere at my end otherwise more people would be complaining about the stems.

Thank you for trying to help, I really appreciate it😉

Band in a box 2024, Build 1114, Windows 10, 32 GB RAM, Intel Core i5-940F 2.9 GHz