I ran the SupportAssist for all options and it reported no issues but the resuming from sleep/hibernate issue still persisted. In the BIOS I enabled "Block Sleep" though, and Windows 10 still does sleep when you close the lid, and now comes back fine as before from sleep/hibernate. I have no idea why this fixes the issue, but it does.
I'm a C/C++ programmer writing a set of KMDF Virtual HID drivers for Windows 10, the steps involved of which according to the Microsoft documentation I've read involve disabling Secure Boot, enabling Test Mode through bcdedit /set TESTSIGNING ON, downloading the Windows SDK and WDK, and remotely provisioning the target computer through Visual Studio 2019 from another host computer.I have an older Windows 10 Dell desktop on this same network which is having no issues in Test Mode with my KMDF test drivers, but is also always on and doesn't go into Hibernate.Once I have set up Test Mode on my Dell Latitude 5490 though, in many cases after trying to resume from hibernate after closing the lid, the computer goes into a boot loop where the white light at the bottom will blink on and off as the screen blinks on and off without showing the Dell logo, and I have to power cycle manually to reboot the whole system. In a few cases I will see a text screen that says, "TPM disabled! F2 to retry boot", yet I have disabled Secure Boot (but TPM is still checked in UEFI settings). In some scenarios I will just get a black screen and I have to power cycle and reboot the whole machine.I see a similar discussion here: E7470 won't wake from sleep, can't upgrade/downgrade bios - Dell Community but re-enabling Secure Boot is not an option in my scenario. What can I do to get this working?
Dell Latitude 5490 hibernate resume issues after going into Test Mode for KMDF 
driver development