Hello Les,
I apologize for my delayed reply.
That is the way I had it configured, but it now randomly works about 10% of the time. I recently moved the CA under Searches and it seemed to work a couple of times, but then it started to fail again with the message still displaying or just erroring out during silent installs. I see the certificate being installed under TrustedPublisher before the message displays, but It may be a timing issue.
As another workaround solutions I can think of you can try:
1. to add a subsequent custom action (after the install certificate action) which will run a sleep command (for a few seconds)
2. or to create three separate MSI setup projects: first one which will include only the certificate installation, the second one which will include only the driver installation, and the third one which will wrap the first two as feature-based prerequisites
Also, I discovered that while doing a silent install, the temporary file property (AI_FILENAME) is not being set for the certificate. This worked in 14.9 and doesn't in the latest.
This could happen indeed if your install certificate custom action is scheduled before the "Paths Resolution" action group. All the temporary files are deployed on disk at install time during the "CostFinalize" standard action (part of the "Paths Resolution" action group). So, a temp file path is not resolved before the "CostFinalize" action.
Hope this helps.
All the best,
Daniel