P: Export isn't resizing exactly to specified long edge

Greetings all, 

I have converted this to a Feature Request (Idea) and given it a little push. No promises...

I can confirm the same results (799 x 531) using an image file cropped to 2848 x 4288. with W blank or 0 and H 800. What's interesting is that Long Edge = 800 produces  an 800 x 531 file and W = 20000 H = 800 produces an 800 x 532 file. Since the 800 side is the only constraint with all three settings they should produce the same results.

Original File Aspect Ratio = 4288/2848 = 1.50562
Long Edge = 800
800/531      = 1.50659 (+.0064% Error)
W = BLANK or 0 H = 800
799/531 = 1.50471 (-.00604% Error)
W = 20000 H = 800
800/532      = 1.50376 (-.1235 % Error)

Looks like rounding differences.  W= 20000 and H= 800 is the least accurate, but it shouldn't be detectable in the onscreen image. For now it's your only choice for constraining mixed landscape and portrait image export resizing on only one side (W or H) with 0 pixel error.

Firstly, it seems that all the images this happened to are verticals. The original dimensions of one image are 2848 x 4288 (Nikon D90) whilst another has dimensions of 3255 x 4883 (cropped slightly from 3264 x 4896, Fujifilm X-T1).

The resize settings I had are below:

What are the dimensions and orientation of the files that resize to 799 and what 'Resize to Fit' settings were you using? I'm not seeing any issues using LR Classic 7.5, but I'll see if I can duplicate it.

That did indeed work, thanks so much. Any idea as to why this has not been resolved in an update?

If you want both portrait and landscape images to be 800 pixels in Height. Use Width & Height with W greater than the width of your widest image file and H = 800. You can save it as a preset. See if this works:

Is there a final solution for this problem? I'm trying to export at a fixed height of 800 pixels high and a number of my files are 799 instead. I'm using Lightroom 6.14. Would love to get this fixed!

I also noticed this issue with the current Lightroom CC 2017. Using export with width & height, and the width set to 0, the height to 2000 pixel. For 2:3 in portrait orientation that does not result in a round number for the width. In 90 % of the cases LR rounds the width and gives me a height of exactly 2000, but sometimes I get height of 1999 pixel.

Making blanks in the the proper sizes, and copy & pasting development settings is the simplest workaround I've found. And doesn't require using a separate program.

Of course, if you aren't using the same sizes regularly; it's not much help.

Yep, it's a long standing bug. The details and a plugin solution by John Ellis are available at this post: https://forums.adobe.com/message/9050627#9050627