Since version 1.43.29, the default path for covers when they are not found locally is the online repository of covers for wM Launchpad by
DeViL303.
The spinning icon will appear if your console doesn't has access to Internet and you don't have the covers stored locally.
To solve this you have the following options:
1- Install the covers pack locally, so the covers can be found or use multiMAN or IRISMAN to download the covers automatically.
2- Enable access to Internet (and in your firewall) to download the covers from wM Launchpad server.
3- Or remove the url specified in COVERS_PATH in the LANG_EN.TXT (or the file for your selected language), like this:
The option 3 is what was changed in 1.43.29+.
EDIT:
It is also suggested to include the title ID in the file name or folder name of your game.
e.g. My game [BLES12345].iso