HDR Develop Setting Sync Errors

Hi all,

I always shoot bracketed RAW and whilst on site typically make a few edits to one of the CR2s to correct perspective and make tonal adjustments before moving onto the next shoot. The intention is then to create HDRs from the bracketed images later and syncronise the settings from the CR2 on site to the HDR. 

Sometimes this works perfectly but other times the perspective correction applied to the HDR goes nuts. It's as if the perspective correction is applied to each of the three images that make up the HDR or something, multiplying the values (I'm likely completely wrong about this). 

The result means I have to re-apply the perpective correction to the HDR - it's a total time-sink. 

Does anyone else have this issue and is there a solution? 

Thanks.