Same bug here, shield not working when crouching.
Just update your game, it is fixed in 1.19.41, I also use Kelly's RTX
This still an issue and never stopped to be, it is now 1.18.12 and nothing has changed for this bug, still can't see the shadow in first person view. If you load a game with RTX on, in first person view you can't see your shadow as perfectly described up here. If you pushed F5 to change to third person view, you will see your own shadow. If you go back to first person view, it isn't there anymore. Very very easy to reproduce the bug.
Same bug with RTX here. I use RTX 2070 Super. My friend on laptop also use RTX and have same issu since 1.17.10
This is by design, a horse with an odd number of health points (15, 17, 19, etc.) does not show the last half-heart.