"original file could not be found" - error using network drives

Hi there,

I save my raw-files for my LR catalog on a separate network drive, to save some space on my Macbook. Normally, that's not a big issue, when I work on some of them: I just need to connect the network drive and (sometimes) re-locate the files (LR seems to have trouble remembering file paths) and set the tick to locate other files as well. Normally, that'll find all my photos then.

Now I've worked on a book and had the photos I used for it saved in a separate collection. I briefly wanted to work on that again and had an exclamation mark in the upper right corner of the photos, signalling me to re-locate the photos again. After making sure the drive was connected, I went ahead locating one of the files, expecting the others to be automatically located as well. But, strangely, it only located files that were in the same sub-folder (those were about three each time). That's also only the case for parts of my library. I keep the file structure from my Canon camera largely unchanged so that the same problem should've applied to other photos as well. But it didn't. And I can definitely access all files manually -- so there shouldn't be a problem with the network drive.

So, I wonder what's causing this, and if there's a way to get LR to keep these connectivity issues to a minimum (i.e. connect once, then it should find all paths and work without any further setup)?

Thanks and happy new year to everyone!

Specs:

MB Pro (late 2013) with El Capitan (v. 10.11.6)

LR 5.6 (with Camera Raw 8.6)

WD Mycloud as network drive