This seems to be the case with all IG's FTSE sector indices.
I was trying to call IG to get an explanation, when I noticed my long trade on FTSE 350 Electronic & Electrical Equipment had just been closed after it hit my stop loss. However, my independent charting software does not show this low level of 8835 being breached at all today! The lowest it has dropped to since the beginning of this year was 9596 on the 8/3/21 (Screenshot attached).
So why has my position been closed out at its stop level today?