ACR update for the Pentax K-3iii PEF RAW files

@robertn89890265, did you delete or rename the old Camera Raw.8bi file?  Are you sure you copied the correct plug-in file from the CC\File Formats folder to the Elements 18\File Formats folder?

Many thanks for your reply. I actually do shoot in DNG RAW format (which is an excellent feature of Pentax cameras), but I would expect Adobe to automatically update the ACR file in Photoshop Elements 2020, as this is supposedly still fully supported by Adobe, on the basis any improvements to the ACR are gained.

Out of interest I tried the official workaround shown below, without success. 

Only the current version of PSE may receive ACR updates. I have seen only once an update for the previous version. The answer from Adobe is that you can always use the DNGconverter to batch convert raw files to the DNG raw format that older PSE versions can read and edit. That's not even necessary in your case because Pentax is one of the smart camera manufacturers who let you shoot directly raw in the DNG format. Why don't you use it?

Note that the current PSE2022 is supposed to read the PEF files from your camera directly.

You'll also find a number of recent posts which explain how you can update the ACR or PSE for recent cameras.

https://community.adobe.com/t5/photoshop-elements-discussions/faq-will-photoshop-elements-work-with-my-camera-or-why-won-t-my-raw-files-open/td-p/4303022