XATA also won’t schedule breakthrough workouts but will warn you with (!) triangle below status stars if your signature becomes stale (no BT events in over 3 weeks). That means you should force the issue when form is blue/green (fresh) by selecting a BT workout from the library and riding it in slope mode. Go ahead an exceed targets if able (without blowing up) then ride to failure with a stand-up sprint (5-7 secs minimum) at end of the long interval just before you collapse. That will ensure signature validation. 
Not sure you stumbled onto this thread when you began your trial but lots of tips here –
Beginner questions - Support - Xert Community Forum (xertonline.com)
If interested in my experience with a full progression cycle see this thread –
Pre-Base to TED; 120+ days; 100% recommended workouts completed at 100% difficulty - General - Xert Community Forum (xertonline.com)
Best way to learn Xert is to experiment as you have been doing, adjusting all the knobs and dials to see what they do.