I recently enabled “Automatically schedule recommended WOTD.” I have Mondays blocked off as unavailable, but yesterday, the planner decided I should do a 40 minute ride anyway. 
Hey Jim,
I’m guessing you have the auto-schedule a recommended workout option. With that enabled, Xert will always pick something, even if you have a scheduled rest day, just in case you still wish to hop on the bike and do something on your rest day! 
Most often, it’ll be a relatively short & easy ‘Active Recovery’ workout selected on a rest day.