Enable Vendor Queueing
Since with Altair Accelerator you will be often running near the edge of saturation of the licenses, you need to enable vendor queueing to add the necessary reliability to overcome occasional situations where licenses are not available due to some out-of-queue activity. For Spectre, the option to use appears to be +lqtimeout VALUE or +lqmmtokens. This is in addition to +lsusp explained below.