I have my screensaver linked to a folder of photos that I have set up to randomly shuffle through.

Place your screensaver files inside Machintosh HD>Library>Screen Savers.  Restart your computer.

Your screensaver files should show up in the left column.

The last 7 are my custom SS.

Next go to Option key>Finder>Go>Library>Preferences.  Trash the com.apple.screensaver.plist file.  Go to the ByHost folder, open same & trash the screensaver plist files that you find.  Most will have a bunch of #s after the name.  Repair permissions & restart your computer.

You're moving the screensaver file & not a folder right?

The screensaver file must look like this and the name ending .saver

I just updated 10.10.3 to 10.10.4 and am having a similar problem. I, too, had a folder in Photos set as my system screensaver (System Preferences/Desktop & Screen Saver) prior to upgrading. Since the upgrade, the screensaver has reverted back to the National Geographic set of pictures, which are pretty but not what I want. When I select "Photo Library..." from the "Source" drop-down menu, I get a window that says "Choose a set of photos to use for the slideshow:" and lists "Photos"  and "iPhoto". When I highlight "Photos", the window on the right says, "Open Photos to see your photos in this list." (see below) Photos is up and running, but no list. I can select an event or album from iPhotos, but I haven't used iPhotos since upgrading to Yosemite, so the pictures aren't up-to-date.

It appears, and I use that word intentionally, that Apple hasn't figured out how to integrate the new "Photos" into the rest of the operating system.

I found my solution — perhaps, Chengers, it will work for you. Of course, I may find that 10.10.4 keeps reverting back to the National Geographic pictures. In my case, it was a simple matter of quitting both System Preferences and Photos. I then reopened Photos and let it completely load. Then I opened System Preferences and selected Desktop & Screen Saver. It took a couple of minutes for the pictures to load (why, Apple, is that so blooming slow?) and, of course, those were the National Geographic pictures. I again selected Photo Library… from the Source drop-down. After a brief time (I went and did something else, so I don't know how slow it was), all of the albums and events from Photos were listed in the sidebar and I was able to select the one I wanted (pictures of my grandson).

I didn't have a problem either until I upgraded to 10.10.4 and, actually, it's very possible that I was using the iPhoto option until 10.10.4 changed my selection to the National Geographic photos. Now that I have the right pictures showing, the shuffle seems to work just fine. Just for kicks — and because they were pictures of my grandson — I watched them for a while and didn't notice any repeats.

Chengers wrote:

 

Apologies - I was just moving a normal folder containing photos to Library>Screen Savers.

 

Sorry for my ignorance, but how do you make it a screensaver file?

 

Thanks again!

Since you are using photos instead of actual screensaver files (.saver) which are animated

, read the following article links.  One of them should work.

Make a Screen Saver Out of Your Own Images in Mac OS X

How to set your iPhoto library as screen saver.  Not sure if the same instructions will work for Photo.  Worth a try.

Mac Basics: Display a screen saver when you're not using your Mac - Apple Support.  Has a few instructions for what you want to do.

My custom screensavers are actual .saver files that I have acquired through the years.  I prefer my screensavers to be animated not static.

You're welcome & good luck!

I'll be MIA for a few days.  However, please keep us up to date on your progress.