Tracks being deleted from database

First off thanks for still supporting LMS, it's a great product that just keeps on giving....

I have LMS (7.9.0 - 145948917) running on an Rpi3, connected to a NAS on the network.

The NAS is not up all the time, it powers up on a Friday evening and down again early Monday morning. Outside these times, I have to manually power it up if I want to use it.

Now, I have ripped a new album and copied it to the NAS. LMS found it and all is good.

A couple of days later, I go to play the album and nothing happens, because I've forgotten to power up the NAS. So the share on the pi has failed etc...
Additionally at this time, the tracks go missing from the database and are never seen again.

So I tried rescanning for changed files and the missing tracks are still missing.

I checked the library.db database and can still see them there in scanned_files, but missing from tracks. Presumably, it is checking the metadata on the actual file to determine if it needs to be re-added to the database.

Is there any way of turning off this behaviour of deleting inaccessible tracks? Or is my only option to do a full re-scan?

Thanks