Ok, so seconed studio shoot on my Canon r5 (shooting raw) with Canon Speed light that im having this issue.
The short Version. when i export from Lightroom after doing my editing, Every few exported photo's are drastically underexposed, but the rest are totally fine. And they all look fine in Lightroom before editing.
Not sure if there may be some strange flash setting in camera that is causing this?
The only solution i have found is to drasticly overexpose the image in lgithrrrom, then export and see how it looks, then do this a few times till the exposer is good. Clearly not a long term solution.
Check out the video to get a better idea of whats going on.
Really strange. I think i know what bug this is and i flagged it months and months ago. Basically, you can apply a setting and Classic doesn't register that the setting has been applied, even though the sliders show it. I think it's related to .xmp writing, but the devs pretty much gave up on helping me troubleshoot. Since the bugged image you have is +3 exposure, the Exported image is being processed without that step because of the bug... i think.