Slow Query Log Only Logs Few Queries

Slow query is enabled but only logs few queries when you retrieve the slow log. It’s been working ok all last week, suddenly this week, it only logs just 2 or 3 queries. Long query time = 0.01 and I expect to see anything above 1sec but this is not the case. I had to query performance schema table to view long running queries instead of the slow log. What could have changed?