Just discovered this as a new problem in LR Classic 8.4, this isn't present in 8.2.
In LR if you hover over a preset in the preset browser a preview of the effect is displayed in navigator and main screen. In 8.4 however if image is in portrait orientation and the preset contains either brush or radial actions these will be incorrectly displayed in the preview - they appear squashed. When you actually apply the preset however they apply correctly.
It seems to be that there was a regression in 8.4 where for some reason it doesn't seem to respect the EXIF orientation field when it previews images like it used to in 8.3.1, as such when it applies a preset with any sort of brush or radial in it then it gets squished with the wrong orientation.
I'm using Lightroom Classic 8.4 with Windows 10, and I'm noticing some weird things related to the preview for presets containing a radial filter, specially when working with portrait-orientation images.
1) If I create a top-left radial filter from a portrait image, then when hovering over it in the Presets panel, the preview will show it on the opposite side (right). But when applying it and moving the cursor away from the preset, it will stay in the right place.
2) If I try to apply the same preset to a landscape image, then both the preview and the applied filter will be on the opposite side.
3) If I create a top-left radial filter from a landscape image, and I choose a portrait image, the preview will be correct as I hover over the preset, but as soon as I click to apply it *and* move away from the presets panel, the real result will be upside-down in the image (it will be bottom-left).
Maybe the fact that presets created on landscape image work the opposite on portrait images is normal (I don't think it should be, though), but I think it's definitely not ok that the preview when hovering doesn't match what you are really getting.
This is a little complicated to understand (all this landscape-portrait-top-left-etc. thing sounds confusing), but if you watch the following video (see below) I think you'll get it (in the video I only show (1) and (2), but you can try (3) by yourselves). The short version is that something seems to be wrong when showing the preview for presets with radial filters on images in portrait orientation.
Updates to Lightroom Classic, Camera Raw, and the Lightroom Ecosystem were released yesterday and contain a fix for this issue. Please install the appropriate update and see if it solves this problem. You can read more about the updates here.
Is it possible the problem still occurs in situation when you're using Smart Previews? I'm using LR classic 9.2.1, just observed the behavior described in this topic and made a quick test. Created Preset containing only one graduated filter (horizontal direction). I mean the 'global Preset', which appears in Presets tab (on the left). Two portrait orientation photos - raw files. For the first one I generated Smart Preview and left the second one as Original only. Then I used Preset preview on both of the photos (just hover the mouse over the Preset). In the first case the preview shew the filter in vertical (instead of horizontal) in the photo. In the second one, it was displayed correctly in horizontal direction. As described at the beginning of this topic, after applying the Preset, the effect was correct for both photos, so it's still the problem with Preview only. Could you please check if you observe the same behavior? And if yes, hopefully it would be easy to apply the fix also to the photos with Smart Previews generated. Thank you