Yeah I discovered that after a while. Weirdly, USB devices were showing up sometimes after sleep and sometimes not, so I'm back using a different thunderbolt SSDT as the hackindrom SSDT was causing all sorts of weird issues on my non-flashed Titan Ridge card (weird Ultrafine audio dropouts and black flashes on the screen).
I had my Titan Ridge flashed for a short while, and it was not working at all with my Ultrafine 5K on Big Sur, so I flashed it back to the v50 firmware. I came across a different Titan Ridge SSDT (KGP's
SSDT-X299-TB3HP.aml), which supposedly is meant for the non-flashed Titan Ridge (had to switch all RP05 references to RP21), and so far it's working great. I guess Thunderbolt isn't actually working on it, but I mainly bought it for the Ultrafine 5K support.