I have merged seven and more, yes overkill.
Now, supposidly LR is supposed to ignore any modificatons you did in LR to your images when merging. But did you do some edits? perhaps tonality?
That said, I have had an issue from time to time, one image in a set fouling it up, intentialy then applied auto tone to the images, and despite LR supposidly ignoring that, they merged.
I have had a few times when nothing would help, had to ignore the one image with the issue.
Apply tonality changes despite LR ignoring that during a merge.
Un apply tonality changes, despite LR ignoring that in a merge
See if removing one or more images from your bracket set, will allow the others to merge.
Adobe stll needs work on the Photo Merge.
P.S. for those not famililar with HDR merge, changing just the shutter speed is prefered.
These are all straight out of the camera. I'm wanting to merge first, then edit once the images have been properly merged. I can merge two images, but when it comes to the third, it just refuses. This is trying across two different photos sets.
All 3 images same file type?
Was this using a zoom, and did you have some zoom creep? In LR, check the cropped dimensons. (View/View options, alter the options)
Also, a similar thread:ERROR: HDR Unable to merge the photos
Might want to post copys of the 3 images, for review.
Edited due to out rite blunders on my part
One JPEG, two unknown
how about screen shots of the RAW files instead, and please include loupe info, default including file name, cropped dimensions will do. (View/ loupe info / show info overlay)
ohh, are you trying to merge JPEG instead of RAW? That SOC statement went right past me, so JPEG?
I don't have an answer for your question (although I suspect you're mixing raws and jpgs).
But this scene doesn't really need HDR – the histogram for the first image has ample space on both sides, and exposing maybe a stop more would give you very good shadow detail without the highlights burning out.
Furthermore, using f/32 ruins your image. At small apertures, diffraction causes significant image degradation. in the form of reduced sharpness. I'm guessing that f/11 (or possibly f/16) would give you sufficient depth of field, if focused in the right spot.
For best image quality, try to avoid smaller apertures than f/11. (f/8 if you're using an APC camera)