Confirmed ovulation but LH surge not being picked up by monitor

Hi, I used the Clearblue Fertility Monitor Touch Screen for the first time this cycle. I started on Day 6 of my Cycle and immediately got High Fertility. I was also using LH (OPK) strips. I had a confirmed rise in LH with my OPK strips on Saturday, but the monitor continued showing HIGH. My LH surge is now gone and the machine is still showing HIGH. I am fairly certain I had my LH surge and ovulation as I was also doing BBT and OPK strips alone with the monitor. Is this common or maybe my monitor doesn't work. Thanks.