Your system specs are not the flex you think they are.
Your system is heavily constrained by the meagre 8 GBs of VRAM of your GPUs. Once Windows takes its cut you’ve got about 6 GB for Redshift to play with. Any other application you have open is also taking a cut the fact you have a Threadripper and 256 GB of RAM is irrelevant. 6GB can disappear surprisingly quickly if you’re using a lot of hires bitmaps in your textures.
Personally I couldn’t work with 8 GBs of VRAM none of my scenes for about 2 years would rendering and I don’t use multiple Apps at once. I’ve no idea what VRAM AE demands but I know Davinci Resolve barely copes with 11 GBs of VRAM when working in 4k with Comps in the Fusion Page and complex colour grades. If I forget to close my web browser I’ll get the dreaded ‘Your GPU is Full’ error in no time. 11 GBs is right on the limit of barely being adequate for my work.
8 GBs is not beast level, 11 GBs is barely fit for purpose, 16 GBs should be the minimum recommended spec and 24/32GB should be what any serious professional should have as base spec for modern content production.
When I update my PCs in a few months, one will have a 4090 for 3D and the other a 4080 (or Mac Studio) for Resolve. Despite having more than double the VRAM of my current systems I still won’t try and multi-task rendering and editing/finishing on the same machine.
There maybe some issue with Redshift returning VRAM after render (that’s not confirmed) but a driver fix is not going to help you run two VRAM hungry applications in the kiddies paddling pool of 6GBs of usable VRAM. You are on a hiding to nothing.