Lightroom’s import preview window says, “Preview Unavailable For This File?”

Hello Community Support Group: 

I hope you understand what I'm trying to say... 

I'm looking for some help with my (Adobe Photoshop Lightroom 6) which I bought approximatly 7 years ago. I havn't had any problems with the Lr software in the past. but now its saying when I import my named folder in Lr:- "Previews Unavailable For This File?

I am recovering from health issues which I've suffered with for the last 3 years, this has stopped me doing many things especially my photography. The camera I have is the (Nikon D500). 

Now I'm starting to recover from my illness & picking my camera up again after many years I'm starting to find my passion for photography again.

I took loads of photos on Saturday 27th May 2023 of my newly born granddaughter which I felt went really well. The camera is set up on the XQD Sony memory card with RAW plus Jpeg* images. (I hope this makes sense).

Today after many years I tried to process the photos I took yesterday through my Lr 6 software but for some reason my photos didn't load up as normal via the import process. It came up as "Preview Unavailable For This File"

I have gone through my Lr library to find some of the older folder I had processed before I took poorly & they open up fine but other folders only showing a limited number of photos in the folder.

If anyone can help with idiot proof instruction I would be most grateful.

William (age 61) grandfather for the first time

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