Stop loss order didn't work


I had an instance when the stop loss order didn’t execute as expected, and my own stop loss routine had to close the position instead. Can anyone help me understand why this happened?
See the attached screenshot which shows the stop limit was set to $6.30 but it didn’t execute and when my own stop limit check executed later on, it cancelled the pending stop limit and then sold at 6.25 to stop loss. Is this a bug?

I can maybe help. What was the parent order number? Was this in paper trading or live?

Thanks Dan, as you might know I asked this on the slack and was answered.