Time in the fits header not correct

I wonder about that. If we are talking about Camera.LastExposureStartTime, the ASCOM documentation reads:
"Reports the actual exposure start in the FITS-standard CCYY-MM-DDThh:mm:ss[.sss...] format."

It doesn't say it has to be UTC - perhaps it is documented somewhere else or perhaps "FITS-standard" implies UTC?

In any case, I imagine getting the UTC from the telescope is generally more reliable.