Can't see previews of images after migration

Hi

I have recently migrated my catalogue from a very old version of lightroom to the most recent but even though the program knows where the files are located it is not showing any previews of my images, just greyed out boxes. I have tried deleting the preview files held but that hasn’t worked. I have also tried changing the colour space but that hasn’t worked either. 

Please help!

Lightroom Classic version: 15.4.1 [ 202606201310-b9f148a4 ]
License: Creative Cloud
Language setting: en-GB
Operating system: Mac OS 26
Version: 26.5.2 [25F84]
Application architecture: arm64
Logical processor count: 14
Processor speed: NA
SqLite Version: 3.36.0
Adobe GSDK Version: 1.4.0.213

Built-in memory: 49,152.0 MB
Dedicated GPU memory used by Lightroom: 60.3MB / 38,338.5MB (0%)
Real memory available to Lightroom: 49,152.0 MB
Real memory used by Lightroom: 979.3 MB (1.9%)
Virtual memory used by Lightroom: 427,402.0 MB
Memory cache size: 0.0MB
Internal Camera Raw version: 18.4 [ 2608 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2
Camera Raw virtual memory: 0MB / 24575MB (0%)
Camera Raw real memory: 1MB / 49152MB (0%)

Cache1: 
NT- RAM:0.0MB, VRAM:0.0MB, Combined:0.0MB

Cache2: 
m:0.0MB, n:0.0MB

U-main: 196.0MB

Standard Preview Size: 1440 pixels
Displays: 1) 1680x1050

Graphics Processor Info: 
Metal: Apple M4 Pro
Init State: GPU for Export supported by default
User Preference: Auto
Enable HDR in Library: OFF
GPU for Preview Generation: Auto (S5_37)

Application folder: /Applications/Adobe Lightroom Classic
Library Path: /Users/jo-jo/Pictures/Lightroom/Backups/2025-03-16 1613/Lightroom 4 Catalog.lrcat
Settings Folder: /Users/jo-jo/Library/Application Support/Adobe/Lightroom

Installed Plugins: 
1) AdobeStock
2) Aperture/iPhoto Importer Plug-in
3) Aurora HDR 2017
4) Export to Photomatix Pro
5) Flickr
6) HDR Efex Pro 2

Config.lua flags: