Hey man,
Welcome. Sorry you’re having issues. Have you downloaded the latest LM here?
Here’s an article on the yellow triangles.
https://inmusicbrands.force.com/akaipro/s/article/BFD3-Troubleshooting-Yellow-Triangles-Successfully-Loading-Audio-Content
What I suggest is removing all content paths in BFD3 and starting fresh. Create one parent folder (ex.BFD Content) on whatever drive you’re using and have all of your expansion root folders in that parent folder. Then have BFD3 rescan for that new folder.
Also, fyi… you can’t use legacy BFD2 core content with this version of BFD3, but you can get a replacement serial which is London Sessions. It has the equivalent content.