As the title said, when I first try to open my default vault on iPad, it got stuck and can’t open anyway until I remove all the files in the vault, so did iPhone.
Then I tried to find out the reason, and actually I just need to remove most of the images in the assets folder (pictures amount from 800 to 100), both apps back to work.
If so, the first launch is a bit wonky. This is because iCloud Drive doesn’t keep everything downloaded by default, and Obsidian needs to read every file. So, it has to work pretty hard to make all of your files available right away.
Generally, this means you should open it, wait a few minutes, then quit and relaunch. You may need to repeat this a few times, especially if you have a lot of files in your iCloud Drive Vault.
Not a nice experience but you should only have to go through it once. No need to delete assets though!