Hello,
I am running into the issue where the logs are returning a failure code of "(Failed to run the action: Display Message. Unknown error (Error: FFFFFFFF; Source: Unknown)" when running the same process as you have detailed above. The title and return code are hardcoded into the powershell script, while the message is inherited through a variable in the task sequence. Even with a timeout aligned to the "Display Message" step that would allow for it to run for a set period of time, the step becomes skipped and no window appears. Have you seen this before, and if so what did you do for the remediation path?