I'm currently feeling your pain. I had been running AI Tool and the older Windows version of DS for some time without much trouble. Recently I upgraded to the latest Windows version of DS and added a Nano, again with the latest DS. I also added a fourth camera for use with AI. I didn't notice any trouble between the short time when I upgraded DS and when I added the camera, but I can't say for sure if there was an issue. However, after adding the camera I started getting the message that all URLs were in use and processing would stop. After 100 images collected in the queue then I started getting messages about the queue being full. After restarting AI Tool it would process images for a bit and then fail again.
I monkeyed with things quite a bit in an attempt to get it working again. I removed the new version of DS and went back to the old one. I removed AI Tool and tried starting over again, but it appears that you can't start fresh just by deleting the AI Tool program folder. After doing so and starting AI Tool, my cameras and settings were still there. The log said that the config file was messed up and that it was restoring from the registry. So I suppose there's some AI Tool settings stored in the Windows registry, or at least somewhere other than where AI Tool resides.
So I decided to try an older version of AI Tool. I think it was 1.8 something, but I still had the same problem. So I gave up and did a bare metal restore from a backup and restored to a point before I upgraded to the newer version of DS and before I added the new camera, and then everything worked as expected. Well, until I added the fourth camera. After that I started getting the messages about all the URLs being in use. I removed the new camera and everything worked as expected again.
I was running the latest AI Tool and the older version of Windows DS on my BI machine. In an attempt to see if the new version of DS had something to do with it I pointed AI Tool only to the Nano. It seems to be working well now but I haven't had much time for testing. If it proves to be acting normal for a day or two then I'll try adding in the new camera.
The camera isn't anything fancy. Just a cheap Reolink RLC-410 that I put part way down my long driveway to see when someone is coming. There's a tree that blows in the wind but I have it masked out in a BI motion zone so it doesn't generate a lot of images to be analyzed by AI. It doesn't make sense but at the moment the new camera appears to be somehow involved. Be it the camera, the act of adding one more camera to AI Tool, or something I haven't yet considered.