As you can see from my Finder example, there ain’t no such thing as “simple” 
I can’t see your point…looks simple to me ?
I don’t want to do anything fancy using metadata etc just rename the files to something simple with a number after it…like Grasmere_001 and need PL8 to keep the order they were taken in.
Most of the time I wouldn’t be too bothered but for my Sports photography it needs to be right.
You checked that you did not have an activated filter, and that the sorting order was correct.
After renamed, the order of images corresponds to an IPTC or exif or other value ?
We could have a screenshot from the Finder with the details of the files.
I’ve just found another reason you need to rename your RAW photo’s in PL8.
If you have worked on images in PL8 and then rename in another programme you lose the work you have done on the images because it loses the connection with the DOP file.
Just a thought - check the sorting order and do what I have found sometimes helps - sort by created date and then name.
That is what I did.
I nearly always sort by date/time taken.
This problem seems to be solved with the latest update 