Ryzen 4700U failing to enter suspend/modern-standby correctly

Brief summary of the problem:

When I close the lid of my laptop, it does not actually enter the suspend/sleep state. The fan is still mildly audible, and dmesg shows some stack traces related to failing to enter suspend.

If I wait a longer period of time (30-45 minutes?), the fan is no longer spinning, but I can see by peeking between the LCD/body that the power-LED is still on (as if the laptop is still on with the fan/screen off). If I open the lid, the laptop does not come back from its pseudo-sleep, and there are no keys that can be pressed that will "wake it" up.

Hardware description:

• CPU: Ryzen 4700U
• GPU: Vega 7
• System Memory: 16GB DDR4 3200
• Display(s): 1x 1080p IPS panel
• Type of Display Connection: internal monitor

System information:

• Distro name and Version: Ubuntu 20.04
• Kernel version: 5.8.0-rc5
• Custom kernel: generic 64-bit kernel image from https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8-rc5/
• AMD package version: None. Currently running libdrm master as of commit 669e1087ab606 and mesa master as of commit 395511d16915297b39d11.

How to reproduce the issue:

Detach power cord, close lid. Wait a few seconds and observe that the CPU cooling fan is still spinning audibly. Let it sit for a while (~1 minute) and re-open the lid. Run dmesg and inspect log for evidence of the suspend sequence.

Attached files:

• Dmesg log taken after closing the lid, waiting 10-15 seconds, and then re-opening it. dmesg