OP-TEE Trusted Application examples fail to run on STM32MP157F-DK2

[Pavestone7762]

I'm attempting to run an OP-TEE Trusted Application on the STM32MP157F-DK2 running OpenST Linux version stm32mp1-openstlinux-6.1-yocto-mickledore-mp1-v23.06.21. I've followed the guides here and here, but both end up producing the following error when attempting to run the application:

TEEC_Opensession failed with code 0xffff0008 origin 0x3

What could be causing this problem? I'm running a fresh install of OpenST Linux and haven't made any modifications to the system other than those required to get the example running.

[Pavestone7762]

I found on this page that OP-TEE user trusted applications are disabled by default for ecosystem release v5.0.0. (It would have been helpful for this to be documented on this page as well...)