Cancelled iui no lh surge cd16

I normally ovulate later cd16-18 but always consistently around this time. After a year of failed trying naturally my doctor recommended iui. I did femara 5mg cd3-7 and am currently on cd16 and haven’t gotten my lh surge yet, but feel lots of cramping and expect it to come tomorrow. Other than the baseline ultrasound they didn’t want to see me until the lh surge. I called the office as instructed since it could land on a Saturday (they said they would give me a different number to call) instead of scheduling the iui they canceled it saying it’s too late in the cycle. So disappointed! Is this normal to cancel it? I thought late ovulation was after cd21