Onedrive Files on Demand not working as described

I am currently having a problem getting Files on Demand working as I would expect. I have done many searches and the problem I am experiencing has been described in many threads since Files on Demand was rolled out ~two years ago without an acceptable solution being provided.

I have three computers that I have setup to back up my Desktop, Documents and Pictures to Onedrive per the settings within Onedrive. I am logged into the same Microsoft account in Onedrive across the three computers. I also back up my photos from my Android phone to the same Onedrive account. All computers are running Windows 10 1903 with Onedrive 19.103.0527.0003 or 19.086.0502.0006 .

The problem I have is that Onedrive is downloading files despite having the "Files on Demand" setting on and no folders set to "Always keep on this device". The problem persists even after "Clearing space" from the affected folders. As far as I can tell it only affects image files (.jpg, .png etc) within the Onedrive Pictures folder. The Documents and Desktop folders behave as I would expect with Files on Demand. Even setting Storage Sense to clear unopened files daily doesn't work.

Based on my testing it appears that Runtime Broken is downloading the image files on behalf of the Windows Photos app. If I kill the Photos app in Task Manager then Runtime Broker with stop downloading pictures. However, Windows will inevitably start Photos and continue to download the images.

I have tried reinstalling Onedrive, Photos and Windows to no avail. Logging into Windows with a Local Account improved things slightly as Runtime Broker would only download images while Photos was open, though this isn't really a solution.

Can someone please point me to a setting to change? Sorry in advance if this is really simple to resolve but I've already spent a week trying to get Onedrive support to assist without a resolution. I am at my wits end. Surely this isn't the behaviour that Microsoft intends and I can't be the only person trying to use Onedrive to back up files with the default settings.

Yo, I think I found the solution!

Check your Photos app settings. At the top, it shows you where it's found photos on your PC. If like me, you've set OneDrive to be your default photos location, it's probably picked up your local OneDrive folder. When it tries to show me my local photos, it blithely tries to show me the 'local' photos, which were actually files on demand from OneDrive. It tells the runtime broker to fetch them for me, and the runtime broker tries to download my entire camera roll. I think that by removing that folder in the photos app, it's stopped the constant downloading of my photos.