P: Sort by capture time should use filename when times are equal

"What's worse, once the stacks were created with Auto-Stack by Capture Time (wrong order), I couldn't select them all and unstack."

Hmm, in my LR CC 2015.8, when I select several collapsed stacks and do Photo > Stacking > Unstack, all of the stacks are unstacked.  Does that not work for you?

Fractional seconds are nowhere in metadata.  Sometimes manufacturers stick it in the proprietary MakerNotes, but not this camera.  (I'm amazed that many manufacturers don't include fractional seconds, and that Adobe still doesn't do a second sort by filename.)

Here are two Olympus raw pics both with time 11:07:31.

Perhaps you could upload a sample raw to Dropbox and post the link here?  I'd like to poke in the metadata to see if fractional seconds are hiding anywhere else.

Same problem with Olympus OMD EM10 II.

I do a lot of macro shots with focus bracketing. The camera does the focus bracketing to get many shots taken as fast as the camera can shoot. I don't use in-camera focus stacking (combining each pic's in-focus areas). I do it in post. 

The Auto-Stack by Capture Time would be sweet if it would sort properly. My stacks are typically 20 to 50 pictures each. I end up with 10 to 20 stacks, so it's somewhat of a chore to create the stacks manually.

What's worse, once the stacks were created with Auto-Stack by Capture Time (wrong order), I couldn't select them all and unstack. I had to open each stack, select only those photos in the stack, then unstack. But, that didn't work. It only removed one photo from the stack. Turns out you can't select the last, then shift-click the first. You have to select the first, then shift-click the last, then unstack works.

I don't see fractional seconds in the EXIF or IPTC metadata for Olympus raw files.

Lightroom CC 2015.8 build: 1099473
MacBook Pro mid 2015
MacOS Sierra 10.12.3

None of those files have the EXIF:SubSecTimeOriginal field, which stores the fractional capture-time seconds.  E.g.

 

I downloaded a couple of sample JPEGs for that camera model from dpreview.com, and the samples didn't have the field either.

Thanks, Mark.
I have sent you an e-mail offline to get some more info.

Thanks,
Sunil

Sunil - this folder: https://db.tt/my3OmOim contains two sets of DNG files that exhibit the problem.

Thanks
Mark

This is the right place to"signal" Adobe -- it's the official place to provide them feedback.  Product developers do monitor and participate here.  The number of me-too votes does influence their prioritization, but it's only one factor among many. 

By the way, you can view all the metadata in a file with the free Exiftool.  

John - your summary of the problem hits the Olympus as well. Just for fun at the time I had a look at the file with a binary editor/viewer I don't see any sub second metadata in the files. So Adobe could make many Sony/Olympus/??? users happier by making this small fix. How do we signal them?

Thanks
Mark