I started encountering an issue with speech output in version 5.2.1 on MacOS 10.14 early 2105 MacBook Pro. I updated MacOS to 12.1 and continued to encounter the issue with speech output. After Smartrace has made a few announcements, all speech output stops. Other sounds, like entering pit lane still work. I could recreate this by going into settings -> sounds and clicking on the speaker button to output the test sounds. After several clicks, the voice will stop outputting sound no matter what announcement I select.
Speech output type was set to Queue Up. Ambient Sound set to empty. Text-to-speech rate is 100%, Countdown Offset is 170%.
I was able to find a workaround by changing the Speech Output Type to Interrupt with all other settings the same and saving. Switching back to Queue Up and saving settings, then going back to test the sounds brings the issue back. Switching back to Interrupt and saving again allows voice output to return.