RHEL7.7 - Cannot "Switch Users" from lockscreen

I am running RHEL7.7 x86_64 w/kernel 3.10.0-1062.7.1 on one system running an AMD FirePro W9100 video card and another system running a Radeon HD 5770.

I am using Gnome Classic as my desktop and after the screen locks (either from SUPER+L or screensaver timeout), I can no longer "Switch User" from the lock screen.

This used to work back in fall 2019, but I do not know exactly when it broke.

I am using the radeon driver in the kernel and whenever I attempt a "Switch User", xorg.log has the following error:

[XORG] (EE) /dev/dri/card0: failed to set DRM interface version 1.4: Permission denied

I can also trigger the same error when switching to a different tty via CTRL+ALT+F2 through F4, logging in as any user (including root), then issuing startx.

In both systems, if I swap in temporarily an nvidia card (using kernel nouveau drvier), user-switching from the GUI works with no issues.

My only hunch is an update to libdrm broke the DRM interface with radeon kernel driver per following, unrelated post about multi-GPU setup with the Bumblebee project:

https://github.com/Bumblebee-Project/Bumblebee/issues/652#issuecomment-167753870

Given it took so long to finally address this issue, I can no longer yum history rollback to fall 2019 since my repos don't store packages that long.

Anyone else run into this issue? Should I open a ticket with Red Hat?

FYI, I am having troubles installing the opensource amdgpu and closed sourced amdgpu-pro and AMD's official response to me is "we don't support RHEL 7.7, only 7.6". My best bet I think is sticking with RH and the radeon kernel driver.