Hi,
This question pertains to Indigo 6.1.11 running under Yosemite 10.10.5 on a late 2008 iMac. The Mac is configured not to auto-logon, and to instead display the username and password fields. Fast user switching is enabled. Normal operation is for me to boot up the Mac, log in as myself using a local account, start the Indigo server and client, ensure everything starts up correctly, leave them running, and then use fast user switching to switch to the login screen. This way, I leave myself logged in with the Indigo client/server running. My kids then log on and off using their own individual local login accounts. When my kids are not actively using the computer, they log out of it, leaving the system sitting at the login screen. Things have been working very well like this for literally years... at least as far back as Indigo 5.
I have a couple of scheduled tasks that have a string in the speak field that cause my Mac to announce things like "House now entering night mode." For some reason, this stopped working some time ago. I don't know exactly how long, because my children occasionally use the Mac to play games and often leave the sound muted to avoid annoying the grownups. I also don't often change things on this particular Mac, because I prefer to keep it stable.
Regardless of when speech stopped working, it now posts in the Event Log in red text, "Error Unable to speak text". This same entry shows up in the Console window. When I am logged in and have my desktop displayed, speech works fine. I tried creating a single schedule that runs every minute to execute a single-line AppleScript that was only say "This is a scheduled announcement." I also populated the Speak field of that action with I just made an announcement. As long as I am logged in, with my desktop displayed, both phrases are spoken every 60 seconds. However, if I stay logged in but use fast user switching to display the user login prompt, nothing is spoken and I get the error posted in the Event Log and the Console.
Assuming this to be a MacOS problem, I created a cron job under my login. The cron job was set to run every minute and execute something like /usr/bin/osascript -e 'say "This is a cronjob"' Then I switched to the login screen, and sure enough, every minute my Mac speaks the cron job text. This tends to suggest to me that the problem has to do with Indigo, and not the MacOS.
Note that I'm not running Indigo server as a daemon. I'm leaving myself logged in with both the server and client running on my desktop. I'm just using fast user switching to leave myself logged in while bringing up the username/password login screen. As I said, this mechanism has worked really well for quite some time now. I can't honestly say when it stopped working. I have updated Indigo more often and more recently than the OS... is it possible one of the Indigo updates broke something?