Missing files on my DATA drive after restoring main w10 drive?

BIt of a strange one this - for me anyway - but maybe a known issue which I hope some maybe able to shed light on?

I still using version Windows 10 1809. On Nov 6th, I imaged my main OS drive (the only personal file on here which gets updated is a Veracrypt file) and also imaged my DATA ssd drive - so two separate images of two separate SSDs.

A couple of days later, my OS drive got corrupted (diagnosing PC etc - wasn't able to repair start-up), so I saved the VC file and restored the image I'd done earlier. After booting back up, I had noticed that the data drive was initally missing a few PDF files saved since the image on the 6th, but shortly appeared - so I thought all good.

Up until yesterday, I have saved a few more PDF files and some PNG files and a foler containing files. For some reason, my OS drive went into diagnosing mode (after updating a quality update), so I restored the image I made on 6th.

My concern now everything's back up is that those new files saved on my separate data drive are not showing. It only shows files up to 6th (when I did images of both drives). Does anyone know what might be causing this?

For info., I've imaged the data drive again using Macrium and free space shows 506mb (free space on 6th image was 540mb) so something is going on here. Maybe something to do with the OS image dated 6th?

Would appreciate any insights.

No idea what happened. I use Macrium for the OS SSD but not for the data D disk. At first I copied all data files from D to an HDD. Later, I synchronize (FreeFileSync) my data D disk and the HDD regularly. It copies only the changes, and gives you a better understanding what is copied and what is deleted.

You can mount the Macrium Image and see if your files are there.