Have you changed the WB setting in the past, or is this image straight out of the camera with no processing preset applied?
Open an image into ACR that is listed as Manual WB.
Take note of the temperature and tint slider values.
Then select Shade from the list of WB presets and note the temperature and tint values.
How much do they vary and which of the two do you consider to be the correct value when looking at the colour values for the neutrals in the colour checker image (i.e. one setting should be more neutral across the tonal range than the other)?
I just looked at some old files in my collection…
For the Olympus DSLR shots in question, the metadata placard shows a “sun” icon… The Filter panel shows “daylight” under white balance – however the Metadata panel > Camera Data (Exif) lists the WB value as Manual. It also appears that the Metadata panel > Camera Data (Exif) will list the Light Source which may or may not help to identify the WB.